KR102174806B1 - Coating liquid, its manufacturing method, ink for electronic device manufacturing, electronic device, organic electroluminescent element, and photoelectric conversion element - Google Patents

Abstract

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 in the organic solvent under the conditions of 50°C or less and atmospheric pressure is in the range of 1 ppm or more and the saturation concentration for the organic solvent. It is characterized by being inside.

Description

Coating liquid, its manufacturing method, ink for electronic device manufacturing, electronic device, organic electroluminescent element, and photoelectric conversion element

The present invention relates to a coating liquid, a method for producing the same, an ink for manufacturing an electronic device, an electronic device, an organic electroluminescent element, and a photoelectric conversion element, and in particular, it efficiently removes moisture or oxygen adhering to an organic material, and is excellent. It relates to the provision of a coating liquid capable of producing a high-performance electronic device, a method for producing the same, an ink for producing an electronic device, an electronic device, an organic electroluminescent element, and a photoelectric conversion element.

1. Dissemination of organic electronic devices and challenges

An electronic device using an organic compound, for example, an organic electroluminescent device (organic elec, Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, etc.) can be used. Various electronic devices such as "OLED", "organic EL device"), organic photoelectric conversion devices, and organic transistors have been developed, and with their technological progress, their spread in various industrial and market fields is progressing. .

For example, an organic EL device, which is a typical example of an organic electronic device, has been used in various fields such as displays, lighting, and indicators, and has already penetrated into the present life with a liquid crystal display or a light emitting diode (LED). Enter, and in the future, we are going to reach a period of rapid expansion of supply.

However, in order to promote the development of organic electronic devices such as organic EL elements, numerous problems to be solved in the process of research and development remain. In particular, various problems resulting from the use of organic compounds remain common to or unique to various organic electronic devices. These problems to be solved can be said to be the ultimate problems that are directly connected to further improvement in performance such as quantum efficiency and light emission life, and further improvement in productivity, that is, cost reduction.

Among the ultimate challenges above, regarding the performance issues, in electronic displays, organic EL elements are already used in the main display of smartphones, and large displays exceeding 50 inches are becoming products and appearing on the market. In lighting and signage, the luminous efficiency of 139Lm/W in white devices, which is approximately twice that of fluorescent lamps, has been achieved, but the luminance half-life of 1 million hours in red phosphorescent devices and green phosphorescent devices has been achieved. In view of the fact that even in the most difficult blue phosphorescent device, results exceeding 100,000 hours are produced, it is considered that the level has already reached a level sufficient for practical use by performing elaborate and fine layer construction and film formation with great care.

On the other hand, in terms of productivity, that is, cost, as described later, the RGB side-by-side display, which is an advantage of the original organic EL device, has not reached mass production for large-sized displays, and reduced production load. The manufacturing method by the coating method developed for the purpose of making it still has a large room for improvement in the purification and handling of solvents and organic materials.

That is, it can be said that solving the problem of low productivity is a necessary condition for developing an organic EL device. In addition, this is considered to be the same for other organic electronic devices, such as organic photoelectric conversion elements.

So, in the following, in particular from the viewpoint of the ultimate problem related to productivity, the problem of the prior art related to the manufacture of an organic EL element which is a typical example of an organic electronic device is demonstrated.

2. Problems with the organic functional layer formation method

First, the problem caused by the method of forming the organic functional layer, that is, the vacuum evaporation method (also referred to as the ``vacuum vapor deposition method'') and the wet coating method (also referred to as the ``wet coating method'' and the ``wet coating film forming method'') will be described. do.

2.1. Effects of moisture and oxygen on organic functional layers

In the organic EL device, electrons and holes are injected into a light-emitting material (generally referred to as a ``dopant'') present in a light-emitting layer, which is one of the organic functional layers, and excitons generated when the recombination occurs are returned to the ground state. The basic principle is to emit light.

Since this exciton is a very active species in an excited state as its name suggests, it readily reacts with water molecules or oxygen molecules to cause chemical changes or state changes such as decomposition or denaturation, and luminescence decreases. That is, it is one of the factors that decrease the light emission lifetime.

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 moisture or oxygen enters in the forming process.

On the other hand, in the organic EL device, unlike LEDs, the presence of the organic compound constituting the light emitting layer is not crystal but amorphous (amorphous) is a condition for highly efficient 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 film formation and the surrounding environment be constant.

Therefore, from the reasons such as the above-described prevention of damage due to moisture or oxygen and the necessity of making the organic compound an amorphous state, the deposition method for the organic functional layer of the organic EL device exhibiting good performance so far was according to the vacuum evaporation method. . The organic EL displays for smartphones, which are already mass-produced, and organic EL displays used in large-sized televisions, also employ a vapor deposition method for forming an organic functional layer.

2.2. Problems of forming organic functional layer by vacuum evaporation method

However, in the case of manufacturing an organic EL device by a vacuum evaporation method, there are the following problems with respect to the emission color reproduction method.

Organic electroluminescence is self-luminous, and since the luminous color is uniquely determined by the light-emitting material constituting the light-emitting layer, basically, red (Red: R), green (Green: G), and blue (Blue: B) A method (RGB side-by-side method) has been employed in which an organic EL element of each luminous color is made for each of the pixels, and arrayed to form a display.

In the case of the RGB side-by-side method, it is necessary to form different light emitting layers for each of the RGB pixels, and in order to perform this in a large area, a method of forming each pixel while shifting the shadow mask for each pixel is common. At this time, since the formation (film formation) of the light emitting layer or the like is a vacuum evaporation method, there is a decisive problem in that the shadow mask is thermally expanded by radiant heat from the evaporation source, resulting in pixel shift.

Due to this critical problem, small to medium-sized displays for smartphones are produced by the RGB side-by-side method and hundreds of millions of panels per year, but for large displays exceeding 50 inches, the manufacturing yield derived from the thermal deformation of the shadow mask. It is low, and large-scale production is not performed.

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

2.3. Possibility of forming organic functional layer by wet coating method

The organic functional layer constituting the organic EL element adopts a lamination structure of about 4 to 7 layers, and the overall layer (film) thickness is about 100 to 200 nm. If it is too thin than this, the anode and the cathode are partially short-circuited due to the influence of the surface roughness of the electrode serving as the underlying layer, resulting in a current leakage phenomenon.

In addition, if it is thicker than this, since the charge conduction mechanism of the organic EL device is a space charge limited current (SCLC) according to the Child's Law, unlike Ohm's Law, the flowing current density is the third power of the distance between electrodes. Since it is inversely proportional, there arises a problem that a large drive voltage rise occurs and the power consumption increases.

Although it is common for the organic functional layer of an organic EL device to deposit a low-molecular compound, instead of a low-molecular compound, a π-conjugated polymer such as polyphenylene vinylene or polyfluorene is used for both carrier movement and light emission. There is also a method of using a light emitting polymer (LEP). Since a polymer material cannot be deposited by vapor deposition, an organic functional layer is produced by a wet coating method (wet film forming method, wet coating method) such as spin coat, die coat, flexo printing, and inkjet printing.

It is also possible to form a smooth coating film on the order of nanometers by appropriately selecting the molecular structure of the compound and the solvent to dissolve, even for a low-molecular compound capable of evaporation.In 2010, Konica Minolta applied four layers of low-molecular compounds. Thus, a prototype of a phosphorescent white device emitting high-efficiency light was presented.

At present, companies and research institutes around the world are actively conducting research and development to produce organic EL devices by this method, that is, a wet coating method (wet coating method) (see, for example, Patent Document 1). .

However, as described later, in the purification and handling of a solvent or an organic material (solute), the problem caused by easily dissolved moisture or oxygen contained in the coating liquid is not sufficiently solved.

Japanese Patent No.4389494

The present invention has been made in view of the above problems and circumstances, and the problem to be solved is a coating liquid capable of efficiently removing moisture, oxygen, etc. adhering to an organic material to produce an electronic device with good performance, a method for producing the same, It is to provide an ink for electronic device manufacturing, an electronic device, an organic electroluminescent element, and a photoelectric conversion element.

In order to solve the above problems, the present inventors, in the process of examining the cause of the above problem, etc., are a coating liquid containing an organic compound and an organic solvent, and dissolved carbon dioxide in the organic solvent under conditions of 50°C or less and atmospheric pressure. When the concentration is within a specific range, it has been found that a coating liquid capable of efficiently removing moisture, oxygen, and the like, and a method for producing the same can be provided, and thus the present invention has been reached. Further, by using this coating liquid, it is possible to provide an ink for manufacturing electronic devices, an electronic device, an organic electroluminescent element, and a photoelectric conversion element with good performance.

That is, the said subject concerning this invention is solved by the following means.

In addition, in order to facilitate understanding of the present invention, the basic policy of the present invention and the process of research and development will be described later.

1. It is a coating liquid containing an organic compound and an organic solvent,

A coating liquid, characterized in that the dissolved carbon dioxide concentration in the organic solvent under conditions of 50°C or less and atmospheric pressure is within a range of 1 ppm or more and a saturation concentration of the organic solvent or less.

2. The coating liquid according to item 1, wherein the dissolved carbon dioxide concentration is in the range of 5 to 1000 ppm under the above conditions.

3. In the case where 1 ppm or more of oxygen is present in the coating liquid, the dissolved carbon dioxide concentration is contained within a range of 1.0 to 100000 times the dissolved oxygen concentration under the above conditions. Described coating liquid.

4. The coating liquid according to any one of items 1 to 3, wherein the coating liquid is a coating liquid for manufacturing an electronic device.

5. The coating liquid according to item 4, wherein the electronic device is a light emitting device.

6. The coating liquid according to any one of items 1 to 5, wherein the organic compound is an organic electroluminescent material.

7. The coating liquid according to any one of items 1 to 6, wherein the coating liquid is an ink jet ink.

8. It is a manufacturing method of the coating liquid which manufactures the coating liquid in any one of Claims 1-7,

A method for producing a coating liquid comprising a step of mixing the organic compound and carbon dioxide.

9. The method for producing a coating liquid according to claim 8, wherein after the step of mixing the organic compound and carbon dioxide, the coating liquid is prepared using a solution containing the organic compound.

10. A method for producing a coating liquid according to item 8 or 9, comprising a step of separating a substance in a solution containing the organic compound using a supercritical fluid.

11. Ink for electronic device production, comprising the coating liquid according to any one of items 1 to 7.

12. An electronic device comprising an organic functional layer formed using the coating liquid according to any one of items 1 to 7.

13. An organic electroluminescence device comprising an organic functional layer formed using the coating liquid according to any one of items 1 to 7.

14. A photoelectric conversion element comprising an organic functional layer formed using the coating liquid according to any one of items 1 to 7.

(Basic policy related to the present invention and the process of research and development)

Under the technical background described above or below, it is estimated that the technology to be employed in the method of manufacturing an organic EL element will inevitably be the next choice.

<Basic policy on manufacturing method>

(1) It is preferable to use a low molecular weight compound as an organic EL compound (high molecular compound is not preferable)

(2) The film forming method uses a coating method (deposition method is not preferable)

(3) The solvent in the coating liquid is preferably a general-purpose solvent (expensive dehydration high purity solvent is not preferred)

(4) Dissolution is preferably in a monomolecular state (microcrystalline dispersion is not preferred)

(5) It is preferable to use adsorption-desorption equilibrium for purification of the compound (thermal equilibrium is not preferable).

First of all, with the basic policies as described above, creating a method that satisfies all policies (3) to (5) is the current technical task, and I believe that achieving it is the most valuable technology, and achieving it. For the means to do it, research and development have been repeated.

As a result, in order to achieve the above ``(3) a general purpose solvent is preferable for the solvent in the coating liquid,'' it is not enough to simply use a dehydration or deoxygenation solvent, and the presence of a special gas in the solution, preferably It was found that the fact that the gas is introduced at a concentration close to saturation increases the robustness of the moisture or oxygen that has been acquired, and although it is very simple, it was found that it constitutes the essence of the present invention. That 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 dissolved oxygen and nitrogen in the atmosphere are exchanged by equilibrium, or by bubbling or pressurizing nitrogen gas to release oxygen, or a method similar thereto. By using, the coating solution was deoxygenated.

However, in the coating process, if the coating solution comes into contact with the atmosphere even for a moment, the coating solution immediately sucks up oxygen or moisture, and the dehydration and deoxygenation coating solution prepared with the utmost care cannot be used, and the characteristics of organic EL devices, especially light emission. It causes great deterioration in life.

The phenomenon we found is that water or oxygen is removed in the initial state of the coating solution, but by infiltrating carbon dioxide close to the saturated concentration into the solution, the solution itself becomes difficult to absorb water or oxygen.

A brief introduction to how we achieved the present invention.

As described above, in the development of coating and forming a film with a low molecular weight compound, a technique for purifying an organic EL material by supercritical high performance liquid chromatography (HPLC) of carbon dioxide was found (Japanese Patent No.4389494). ).

However, there has been found a problem in that the performance fluctuates each time an element is fabricated due to contact with air in the film forming process or contamination by moisture or the like adhered to the coating device in a small amount.

The inventors of the present invention have conducted a thorough study aiming at solving the problem. As a result, when supercritical carbon dioxide escapes from the solution as gaseous carbon dioxide, it completely takes dissolved oxygen out of the solution system, and that water contained in trace amounts is also Knowing that it escapes by hydrogen bonding and that carbon dioxide remaining at a concentration close to saturation prevents the incorporation of oxygen or water into the solution system, the eluent purified from supercritical HPLC was applied as it is. It was found that it was possible to fabricate a device with high performance, almost no change in performance, and stably good, and came to the present invention.

Further, it was found that not only supercritical carbon dioxide but also when carbon dioxide gas is bubbled into an organic solvent solution of an organic EL material that is usually dissolved, the same effect is exhibited even by contacting it.

Summarizing the description so far, the present invention is constituted by the following technical elements.

In addition, the description up to this point has been a description of an organic EL device by a coating film forming method using a low molecular weight compound, but this is only one of the most representative and most effective applications, and other electronic devices coated with a low molecular weight compound to form a film, Needless to say, the same technique can be applied to, 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) Coating solution in which the solute is dispersed in a solvent through adsorption-desorption equilibrium

That is, by using the supercritical carbon dioxide HPLC purified eluent in a state that is not completely concentrated and dried, the above (a) to (c) are achieved at the same time, but the present invention is not a prerequisite, but dissolved with carbon dioxide, and adsorption-desorption The method can be used as long as it has undergone equilibrium and is dispersed (ie completely dissolved) in a solvent.

A coating liquid capable of efficiently removing moisture, oxygen, etc. adhering to an organic material by the above means of the present invention to produce an electronic device with good performance, a manufacturing method thereof, an ink for manufacturing an electronic device, an electronic device, an organic electro It is possible to provide a luminescence device and an organic photoelectric conversion device.

The mechanism for expressing the effect of the present invention or the mechanism of action is not clearly defined, but is speculated as follows.

The coating liquid of the present invention has a dissolved carbon dioxide concentration in the organic solvent of 1 ppm or more and a saturation concentration of the organic solvent or less under the conditions of 50°C or less and atmospheric pressure, so that the carbon dioxide dissolved in the solution before and after coating When it escapes as gaseous carbon dioxide, dissolved oxygen is taken out of the solution system together, and water contained in a trace amount in the solution is also removed by hydrogen bonding with carbon dioxide. In addition, the carbon dioxide remaining at a concentration close to saturation can prevent the incorporation of oxygen or water into the solution system. As a result, a high-performance electronic device can be manufactured, and the yield can be improved. Carbon dioxide in the present invention is dissolved in the coating solution for the purpose of removing oxygen or water in the coating solution and preventing the incorporation of oxygen or water into the coating solution, and is not used as a medium for spraying, for example. .

1 is a comparison between a vapor-deposited film and a coated film: analysis results of particle size distribution of fine particles of organic compounds in a film.
Fig. 2 is a comparison of a vapor deposition film and an improved coating film: analysis results of particle size distribution of fine particles of organic compounds in the film.
3 is a schematic diagram of an apparatus using a packed column in a supercritical fluid chromatography method.
4 is a schematic diagram showing an example of a display device made of an organic EL element.
5 is a schematic diagram of the display portion A.
6 is a schematic diagram showing a circuit of a pixel.
7 is a schematic diagram of a passive matrix system full color display device.
8 is a cross-sectional view showing a solar cell including a bulk heterojunction type organic photoelectric conversion element.
9 is a cross-sectional view showing a solar cell including an organic photoelectric conversion element having a tandem bulk heterojunction layer.
10A is a schematic configuration diagram of an organic EL full color display device.
10B is a schematic configuration diagram of an organic EL full color display device.
10C is a schematic configuration diagram of an organic EL full color display device.
10D is a schematic configuration diagram of an organic EL full color display device.
10E is a schematic configuration diagram 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 in the organic solvent under the conditions of 50°C or less and atmospheric pressure is in the range of 1 ppm or more and the saturation concentration for the organic solvent. It is characterized by being inside. This feature is a technical feature common to or corresponding to the invention according to each claim.

As an embodiment of the present invention, it is preferable that the dissolved carbon dioxide concentration is in the range of 5 to 1000 ppm under the above conditions from the viewpoint of manifesting the effects of the present invention.

In the case where 1 ppm or more of oxygen is present in the coating liquid, the dissolved carbon dioxide concentration is contained within the range of 1.0 to 100000 times the dissolved oxygen concentration under the above conditions from the viewpoint of stability of a device prepared using the coating liquid. desirable.

It is preferable that the said coating liquid is a coating liquid for electronic device manufacturing from the viewpoint of being able to manufacture an electronic device of favorable performance, and it is preferable that the said electronic device is a light emitting device.

It is preferable that the organic compound is an organic electroluminescent material from the viewpoint of light emitting device life and light emission efficiency.

It is preferable that the coating liquid is an ink jet ink from the viewpoint of manufacturing 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 process of mixing the organic compound and carbon dioxide, it is preferable to prepare the coating liquid using a solution containing the organic compound. That is, the carbon dioxide contained in the coating liquid is preferable in that it is possible to prevent foreign matters from entering the coating liquid by contacting air in the film forming process or moisture adhering to the coating device in a small amount. In addition, there is no need to perform a step of preparing a coating liquid by re-dissolving the purified organic compound in a solvent suitable for coating film formation after concentrating to dryness.

Having a step of separating a substance in a solution containing the organic compound using a supercritical fluid is preferable from the viewpoint of efficiency of the purification step.

The coating liquid of the present invention is suitably contained in an ink for electronic device manufacturing.

The coating liquid of the present invention is suitably used for formation of respective organic functional layers of electronic devices, organic electroluminescent elements, and photoelectric conversion elements.

Hereinafter, the present invention, its constituent elements, and forms and aspects for carrying out the present invention will be described in detail. In addition, in this application, "to" is used by the meaning including the numerical value described before and after that as a lower limit and an upper limit. In addition, in the present invention, "ppm" represents "ppm by mass".

(Summary 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 in the organic solvent under the conditions of 50°C or less and atmospheric pressure is in the range of 1 ppm or more and the saturation concentration for the organic solvent. It is characterized by being inside.

As described above, the present invention has been completed by examining based on the following basic policies (1) to (5).

(1) The organic EL compound is preferably a low-molecular compound (high-molecular compound is not preferable)

(2) The film forming method uses a coating method (deposition method is not preferable)

(3) The solvent in the coating liquid is preferably a general-purpose solvent (expensive dehydration high purity solvent is not preferred)

(4) Dissolution is preferably in a monomolecular state (microcrystalline dispersion is not preferred)

(5) It is preferable to use adsorption-desorption equilibrium for purification of the compound (thermal equilibrium is not preferable).

In the following, first, the present invention is explained from the viewpoint of the basic thinking method that serves as the basis for each of the above policies, and thereafter, a specific technique is described.

1. Advantages of low molecular weight compounds over high molecular weight compounds

In the formation of the organic functional layer by the wet coating method, the superiority of the low molecular weight compound to the high molecular compound will be described.

(Factor 1): The superiority of purity

When comparing a low molecular compound with a high molecular compound (so-called polymer), the difference can be clearly seen. First, a low molecular weight compound is suitable for application of sublimation purification because of its small molecular weight, and a small molecular weight distribution of recrystallization is preferable. In addition, a method for purifying a low-molecular compound is preferable because high performance liquid chromatography (HPLC) or column chromatography having low purification efficiency (low number of theoretical stages) can be used.

In the purification of a high molecular compound, in most cases, purification is carried out by repeatedly performing a reprecipitation method using a good solvent and a poor solvent, and the low molecular compound is more likely to have high purity.

In addition, 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 there are many cases in which a reactive substituent remains at the end of the polymerization. It is also one of the reasons for high purity.

(Factor 2) Advantages regarding the specific energy level of molecules

Light emitting polymer (LEP) is a π-conjugated polymer as its molecular weight increases, so the conjugated system expands to stabilize the molecule, so in principle, the energy level of the singlet or triplet excited state and the ground state The difference (also referred to as "energy level gap" and "band gap") narrows, and blue light emission becomes difficult. In addition, in blue phosphorescence requiring a higher energy level (greater energy level difference) than that of blue light emission of fluorescence, it is structurally difficult for the light-emitting polymer to form a transition metal complex as the light-emitting material. Further, even if a light-emitting polymer is used as a host, it is difficult to obtain a compound having a high triplet energy (abbreviated as a "high T ₁ compound") due to the expansion of the?

In addition, thermally activated delayed fluorescence (TADF), which has recently attracted attention, has not been accomplished with a π-conjugated polymer, and it is difficult to use it as high-efficiency blue light emission with high market demand.

On the other hand, in the low molecular weight compound, there is no inevitability to connect the π conjugated system, and aromatic compound residues that will become the π conjugated units are required, but they can be selected arbitrarily and they can be substituted at any position. Therefore, in a low molecular weight compound, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and the triplet (T ₁ ) energy level can be purposely adjusted, and blue phosphorescence It is also possible to make a light-emitting substance, to use it as a host, or to construct a compound that causes the TADF phenomenon. In this way, the degree of scalability that can intentionally design and synthesize an arbitrary electronic state or an arbitrary level is a factor of the second advantage of the low molecular weight compound.

(3rd factor): ease of compound synthesis

Although it is a similar reason (factor) to the second factor, the low molecular weight compound is not limited in the molecular structure that can be synthesized compared to the light-emitting polymer (LEP).In particular, if the main chain is π-conjugated in the light-emitting polymer, it is applicable. Although the possible skeleton and synthesis methods are limited, it is relatively easy to achieve new functions and adjustment of physical properties (Tg, melting point, solubility, etc.) by molecular structure in low-molecular compounds, which is the third advantage of low-molecular compounds. .

2. Problems in Formation of Organic Functional Layer by Wet Coating Method Using Low Molecular Compounds

What is the essential problem in forming an organic functional layer by a wet coating method using a low molecular weight compound is demonstrated.

Almost all materials used in organic EL devices require electrons and holes to hopping between molecules within the organic EL device. Basically, electrons are hopped using the LUMO level, and holes are hopped using the HOMO level.

That is, if the π-conjugated system does not exist so that the π-conjugated system overlaps with each other, it is advantageous to form a molecular structure only with the π-conjugated system unit 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, π The conjugated system becomes difficult to overlap, and the hopping movement is inhibited in the part of the bulky substituent.

On the other hand, since the organic EL element constantly flows current during light emission, even if the quantum efficiency is 100%, that is, the probability of carrier recombination is 100% and the heat deactivation is 0%, the organic EL element continues to carry carriers. Because of the flow, it is necessary to set an electric field gradient by setting a potential difference between the anode and the cathode, so that the equivalent circuit of the organic EL element is connected in series with a diode and a resistor.

In other words, it is also known that Joule heat is generated inside the organic EL element during electroluminescence, and heat generation of 100°C or higher is actually generated inside the element, especially in the light emitting layer where recombination occurs.

In addition, since the organic layer thickness of the entire organic EL device is a very thin layer of about 200 nm, heat is conducted between layers (films), so that a high temperature state continues in all layers, not only the light emitting layer.

Organic molecules exposed to such a state cause a phase transition from an amorphous state to a crystalline state when it exceeds its own glass transition point (Tg).

This crystal grows gradually, and when it exceeds several tens of nm, the layer thickness in which the compound exists is exceeded, and since functional separation by the layer as an organic EL element becomes impossible, as a result, the luminous efficiency decreases.

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 through the minute region, causing thermal decomposition of the organic compound in the portion, resulting in a portion that does not emit light completely, or a so-called dark spot.

That is, the low molecular weight compound of the organic EL device must be a molecule which does not have a bulky non-aromatic substituent and has a glass transition point (Tg) exceeding 100°C (preferably 150°C or more).

In order to construct such a molecule, the π conjugated system is usually enlarged or the aromatic group is simply connected.However, in the usual case, the solubility of the compound in the solvent is very low, so that it cannot be a coating solution, or even if it is applied, crystal precipitation Or the ubiquity of substances.

As a means of solving this dilemma, we have developed a breakthrough technology that can form a stable amorphous film and maintain it even while energized (for example, Japanese Patent No. 5403179 or Japanese Patent Laid-Open No. 2014-196258). Specifically, it does not have a bulky, highly flexible branched alkyl group, etc., and connects only an aromatic group to form a via-aryl structure, and a number of conformations and geometric isomers are formed by rotational disturbances occurring around the CC bonding axis. Since the number of components in the film can be increased by actively increasing or by allowing multiple molecules (eg, host and dopant) present in the same layer to interact in various shapes and forms, it is possible to increase the number of components in the film. By increasing the entropy of, a stable amorphous film can be formed.

The present inventors improved the molecular structure of the low-molecular compound in accordance with the guidelines described above in the manufacture of an organic EL device by a wet coating method, and also tried to optimize drying conditions, and the luminous efficiency was 95% of that of the evaporation device. In addition, the light emission lifetime was able to achieve a remarkable improvement of 90% of the evaporation device. Thereby, it was found that even in a device using a phosphorescent dopant as a light emitting dopant, particularly a blue phosphorescent dopant, which is said to be the most difficult to improve the lifetime, by the coating film forming method, the basic properties almost comparable to the conventional vapor deposition film forming method can be exhibited.

However, many problems still remain in the organic EL device with improved performance as described above.

As such a subject, for example, the purity of the low-molecular compound, the trace moisture adhering to the surface of the compound, the oxygen content of the solvent to be used, the moisture content, etc. can be removed.

In addition, for example, even for low-molecular compounds generally used in coating, in order to exhibit the best performance, column chromatography and recrystallization are performed, followed by sublimation purification, and when using or storing organic compounds, they are subjected to a vacuum state. After that, it is used by replacing it with a nitrogen atmosphere.

Even when the organic EL device was fabricated by the coating method under very strict control, excluding such adverse effects as much as possible, it was difficult to exceed the performance of the organic EL device fabricated by the vapor deposition method.

In addition, since the low productivity of the vapor deposition method using a vacuum adversely affects the large-sized and mass-produced organic EL elements, that is, the cost, the coating method is attracting attention, but the coating method is also carried out under such strict control. The productivity is lower and it becomes high cost.

3. How to purify the compound

The advantage of low-molecular compounds is that they can utilize more purification means than high-molecular compounds and can be made with high purity. However, in the end, in general, almost all of the organic compounds constituting the organic EL device currently in practical use are used through purification means called sublimation purification.

Sublimation purification is a classical purification method, but the purification efficiency (the number of theoretical stages) is overwhelmingly small compared to purification methods such as recrystallization, column chromatography, and HPLC. In reality, it is used to remove metals or inorganic substances and remove solvents. It is being used as a means.

When it comes to why sublimation purification is employed in organic compounds for organic EL, the main reason is that the organic EL device manufacturing process employs a vacuum evaporation method. If the organic compound contains even a very small amount of the solvent, the solvent in the organic compound is evaporated when placed in a vacuum in the vapor deposition apparatus, thereby lowering the degree of vacuum.

That makes serial production impossible and becomes a manufacturing problem. Therefore, a sublimation purification method is employed in which the solvent is completely removed during purification.

Therefore, when the production method of the organic EL device is replaced by the deposition method from the coating method, purification of the organic compound by the sublimation purification method is not essential for the reasons described above.

(Recrystallization)

Next, the most common recrystallization method is considered as a purification method for a low molecular weight organic compound.

This method is a purification method based on the second law of thermodynamics (Equation 1).

-ΔG=-ΔH+TΔS… (Equation 1)

For substances, as the distance between substances becomes shorter, the van der Waals force, hydrogen bonding force, π-π interaction force, dipole-dipole interaction force, and the like 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 roam freely, so that the messiness increases, and the entropy (ΔS) increases.

In the second law of thermodynamics, all states of existence are shifted in the direction of keeping the Gibbs' free energy (-ΔG) constant or increasing it.

That is, to purify the compound A to be purified by recrystallization can be reasonably explained by thinking as follows.

When A is dissolved in a solvent called B that can dissolve A, A is present in a dispersed state. Therefore, since the existence distance between A is large and it becomes difficult to interact with each other, the enthalpy (-ΔH) becomes very small.

On the other hand, the entropy (ΔS) is very large because A can freely move around in the solution. When this hot solution is cooled, TΔS to which the absolute temperature T is applied becomes smaller than before cooling. At that time, in order to keep the free energy (-ΔG) of the casts constant before and after cooling, the enthalpy (-ΔH) must be increased.

In other words, as the temperature decreases and TΔS decreases, the enthalpy of A must be increased by reducing the distance from A. The extreme state is a crystal state in which the distance between A and A becomes the minimum, and thereby 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 as the enthalpy decreases, crystals are formed to increase the enthalpy.

In this way, first, the entropy term (TΔS) is decreased due to a decrease in temperature, and the enthalpy (-ΔH) is increased by crystallization to compensate for it, and the number of components is thereby reduced, so that the entropy term is, this time ΔS Recrystallization is accomplished by repeating the thermodynamic equilibrium that decreases by the decrease of and crystallization occurs accordingly.

However, what should be noted is the interaction between solute A and solvent B. Since solute A dissolves by solvating with solvent B, if the interaction between A and B is not large, A does not dissolve in B at first. However, if the interaction is too large, the distance between A and A cannot be shortened as much as it overcomes the decrease in the entropy term that decreases due to cooling (because B is interposed between A and A), resulting in no recrystallization. do.

That is, this recrystallization method can be applied only when the interaction force of A-A and the interaction force of A-B can be adjusted under the conditions in which recrystallization occurs. In such a recrystallization purification method, since a large amount of purification of several hundred Kg or more at a time is possible, 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 bar of column chromatography is that fine particle silica gel is used for the stationary phase, compound A is adsorbed thereto, and it is gradually eluted with a mobile phase (B) called an eluent.

At this time, with respect to the interaction (adsorption) of the silica gel surface and the compound A, when the interaction with the mobile phase (B) is antagonistic, A repeats the adsorption-desorption equilibrium between the silica and the mobile phase B, When the interaction of is small, it elutes quickly, and when the interaction is large, it elutes slowly.

At this time, since the number of theoretical plates (that is, purification efficiency) increases as the number of round trips in the adsorption-desorption equilibrium increases, the purification efficiency by chromatography is proportional to the length of the stationary bed and proportional to the passage speed of the mobile bed, and the surface area of the stationary bed Is proportional to

This is achieved by high-performance liquid chromatography, which is widely used for component analysis and quality assurance of organic compounds, which is due to the fact that it is a rare method capable of realizing a high number of theoretical plates supported by this theory.

The reason why this chromatographic method is superior to recrystallization is that the polarity of the mobile phase B can be arbitrarily changed. For example, the number of theoretical plates can be increased further by using a gradient method that gradually increases the ratio of the good solvent during purification, as well as making the mobile phase a mixed solvent of a good solvent and a poor solvent from the beginning. have.

In addition, since it is possible to change the temperature arbitrarily, the application range of the solute that can be purified is very wide, and the greatest feature is that it can be utilized as an almost universal purification method.

On the other hand, there is also a drawback of the chromatographic method. As described above, the fundamental principle for increasing the number of theoretical plates is that the adsorption-desorption equilibrium is utilized.

For example, when chromatography is performed using only a solvent B'(that is, a good solvent) having a strong interaction with compound A in the mobile phase, the interaction between A and mobile phase B'is stronger than the interaction between A and silica gel, The number of reciprocations of 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 poor solvent C in addition to the good solvent B', and increase the number of reciprocations of the adsorption-desorption equilibrium. However, in this case, a large excess of C is contained in the purified and fractionated solution of Compound A, and the greatest problem is that it must be concentrated.

For example, in order to obtain 1 g of A, it is necessary to set the mixing ratio of good solvent B'and poor solvent C to about 1:99 to 10:90, and generally, poor solvent C of about 10 L to 100 L is required. Discard it. Therefore, although HPLC preparative is applied to research and development, it is not used for mass production.

The means to solve the problem of concentration of poor solvent is HPLC using supercritical carbon dioxide. Supercritical carbon dioxide is made of carbon dioxide as a supercritical fluid at high temperature and high pressure, and other substances can be used as such a supercritical fluid, but since it can achieve a supercritical state at a relatively low pressure and temperature, chromatography or extraction Only carbon dioxide is used in

This supercritical carbon dioxide has characteristics different from ordinary fluids and liquids. That is, by changing the temperature and pressure, you can continuously change the polarity to match the polarity of what you want to dissolve.

For example, when selective extraction of docosahexaenoic acid contained in fish heads, this supercritical carbon dioxide is used, and even for cleaning special clothing using adhesives, it is a supercritical solution that dissolves sebum and does not dissolve adhesives. It accomplishes this by making carbon dioxide by controlling temperature and pressure.

Although it is supercritical carbon dioxide that can have various polarities as described above, the polarity of supercritical carbon dioxide formed by relatively low temperature and pressure is about cyclohexane or heptane. In the currently commercially available supercritical HPLC, supercritical carbon dioxide of this degree of polarity is produced in an apparatus, and it is mixed with a good solvent to enter the column, and the compound is purified by a mechanism similar to that of ordinary HPLC.

In the HPLC system using supercritical carbon dioxide, it enters the detector after passing through the column, but usually, a high temperature and high pressure state is maintained until that stage, and carbon dioxide also exists as a supercritical fluid. Thereafter, carbon dioxide becomes a gas during fractionation at room temperature and pressure, and during fractionation, the carbon dioxide itself escapes from the solution, so that concentration of the poor solvent becomes unnecessary. At this time, it is possible to recover carbon dioxide by a carbon dioxide recovery device equipped with a gas-liquid separation mechanism described in the reference literature (Journal of Biological Engineering, Vol. 88, No. 10, pp. 525 to 528, 2010), and again used as a supercritical fluid. It is also possible.

For this reason, in the pharmaceutical industry, where it is necessary to synthesize numerous high-purity new synthetic compounds, this supercritical HPLC has recently been actively utilized, and due to its influence, sales prices for both analysis and preparative use have fallen, and are quite commonly used. Came to be.

From these characteristics and circumstances, we have used this supercritical HPLC to purify an organic EL material requiring high purity (Japanese Patent No. 4389494).

As described above, while productivity improvement in the organic EL industry is desired, there are various methods for purifying low-molecular organic compounds, but none of them have one or the other, and the properties of the prepared compound, the purity required for the compound, and residual Depending on the availability of the solvent or the like, a suitable purification method is selected or used in combination.

4. Dissolution of organic EL compounds

First of all, think about what dissolution is. Normally, it is said that the solvent molecule B surrounds the solute A with the interaction force of A and B, and the aggregate of A is scattered so that B exists around A, that is, the A is in an isolated single molecule state. It is difficult to see if it works.

For example, when A is a molecule having very low solubility or high crystallinity, if it is a crystal having a size equal to or larger than the wavelength of visible light, what is not dissolved can be easily detected by light scattering or the like. However, in the case of a substance with moderately low solubility, for example, even if a solvent molecule B surrounds a crystal containing several molecules of A, it appears to be dissolved. In the organic EL device, this may cause a big problem in the future.

That is, in vapor deposition, 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 compound constituting each layer is basically vaporized by vacuum evaporation. It lands on a substrate or an organic layer in a state, and it becomes a solid thin film and is deposited. For this reason, basically, a film is formed from a random aggregate of single molecules, resulting in an ideal amorphous film.

On the other hand, in the case of the coating film forming method, if, for example, the coating solution is a microcrystalline dispersion of an organic EL compound, it appears to be completely dissolved in appearance, but the actual state of the obtained thin film is a thin film in which microcrystals are collected. Therefore, for example, the level of HOMO and LUMO is not that of a single molecule, but that of a stack aggregate (crystal state), and may be a factor of performance degradation.

In addition, over time, since the microcrystals become nuclei and grow into coarse crystals, not only the functional separation between layers becomes impossible, but also a large crystal that short-circuits the anode and cathode causes dark spots to be generated. there is a problem.

Regarding the coating film forming device using a low molecule, based on the above-described long period of study, how to approximate the initial coating solution to a monomolecular dispersion state becomes a necessary condition for achieving the same performance as the vapor deposition method. It is clear.

Here, in general, the degree of molecular dispersion of the coating liquid intended to be strictly dissolved is analyzed by small angle X-ray scattering (also referred to as ``SAXS''). Think based on it.

1 is a particle diameter distribution curve (horizontal axis: particle diameter (nm), vertical axis: frequency distribution) of a compound constituting a thin film produced by a vapor deposition method with a broken line, and the solid line is the particle diameter of the fine particles of the thin film constituent compound prepared by the coating method Distribution. Since both are using the same compound, they can be compared directly.

The particle diameter distribution width of the fine particles of the compound in the vapor deposition film formation is about 2 nm in the particle diameter at the position corresponding to the maximum peak, and the particle diameter is close to monodisperse. This indicates that an amorphous film is formed by arranging almost single molecules randomly in the vapor deposition film formation in terms of the size of one molecule or two.

On the other hand, in the particle size distribution of the fine particles of the compound in the coating film formation, the particle diameter at the position corresponding to the maximum peak is about 4.5 nm, and is more widely distributed than the particle size distribution in the vapor deposition film.

As described above, since the same compound is used for deposition and coating, the original crystallinity and cohesiveness of the compound are the same, and this difference is that the dispersion state of the molecules in the state of the coating solution is different from that of the single isolated molecule. It is presumed that it was a microcrystalline dispersion of 5 to 10 molecules.

Of course, even if this coating solution is stored in a glove box under a nitrogen atmosphere for more than one week, crystals do not precipitate, and it is a so-called clear solution, but when interpreted by X-rays, a few molecules of microcrystalline dispersion, we are a dissolved solution. They are mistaken.

Next, the result of examining the particle diameter distribution of the coating thin film produced by the coating solution used for the prototype in which the compound was improved and the adjustment method of the coating solution was improved is shown in FIG. 2 by the same analysis.

As is clear from this result, it can be seen from the results shown in Fig. 2 that there is almost no difference in particle size distribution of the fine particles of the organic compound in the vapor-deposited film and the coated film.

In this way, we confirmed during this review that by improving the molecular structure and devising a dissolution method, it is possible to create a completely dissolved state in which almost isolated single molecules are dispersed.

Although this was a great achievement that proved that the organic EL device produced by the coating method can exhibit the same performance as the organic EL device by the evaporation method, on the contrary, we, the device by the coating method, are equivalent to the device by the vapor deposition method. In order to do that, I also found out that there was a huge process load.

In other words, in order to achieve the same performance as the evaporation method with the coating method in the current situation, it is necessary to carry out a very laborious process such as a dissolution method or a storage method, even though the coating method is expected to have excellent productivity. When this increases, there is a high risk that this process will become a rate controlling process, and it is strongly recognized that improving this technical area is indispensable for mass production in the future.

5. On the purity of the solvent of the organic EL compound

The organic EL device has as a basic function a phenomenon in which light is emitted when a light-emitting material that has entered an excited state returns to a ground state.

Further, it is necessary to transport electrons and holes through a hopping phenomenon between the electrode and the light emitting layer.

First of all, as for 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 emit light continuously for one year at a luminance of 1000 cd/m2, simply calculate, and one dopant is approximately You need to be an exciter 1 billion times. At this time, even once, when an exciton reacts with a water molecule, it becomes a compound different from the original molecule. Further, when an exciton reacts with an oxygen molecule, some oxidation reaction or oxidation coupling reaction occurs. This is the most representative phenomenon of chemical change that causes deterioration of the function of the organic EL device.

In addition, for materials other than the light-emitting material, the radical state is formed almost the same number of times, and the radical anion state and the cation radical state are active species compared to the ground state, which causes the deterioration of the function of the organic EL device. There is a possibility of a chemical change occurring.

In other words, water molecules and oxygen molecules must not be present in the coating liquid at all, and that is the premise.

However, industrially, an anhydrous solvent with high purity is very expensive and it is difficult to handle. Therefore, in the end, in order to reduce the cost in the coating method, it is important how a solvent serving as a consumable can be used as a general purpose.

6. Storage of organic EL materials as solutes

As described above, the presence of water and oxygen is estimated to be a fatal defect in the performance of the organic EL device, particularly in the life of the light emitting device.

It is no exaggeration to say that the most indispensable thing in the coating method is to prevent the incorporation of water and oxygen, and for that purpose, neither the solute nor the solute can be left in the air in a powder state like ordinary reagents and chemicals.

When we manufacture a coating film forming element, usually, a material that is a solute is put in a mechanism such as a flask or a shrink tube that can perform both decompression and inert gas purge, and the pressure is reduced with a vacuum pump, while using a heat gun or the like. It is a common method to heat a container, and after sealing it with nitrogen, transfer it to a glove box under a nitrogen atmosphere, dissolve in a dehydrating solvent therein, and form a coating film in a state of nitrogen underneath.

At this time, in order to completely remove oxygen, nitrogen gas is also bubbled through the dissolution, and the dehydration solvent is also passed through an absorption tube of alumina or zeolite immediately before dissolution and used. These treatments are the same or similar to those in pilot plants and actual factories, but the fact that this process takes a very long time and lowers productivity is as described above, and solving this part is our greatest challenge. Is thinking.

7. About the elemental description of the present invention

[Application 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 in the organic solvent under the conditions of 50°C or less and atmospheric pressure is in the range of 1 ppm or more and the saturation concentration for the organic solvent. It is characterized by being inside.

In addition, it is preferable that the dissolved carbon dioxide concentration is in the range of 5 to 1000 ppm under the above conditions.

In addition, when 1 ppm or more of oxygen is present in the coating liquid, the dissolved carbon dioxide concentration is contained within the range of 1.0 to 100000 times the dissolved oxygen concentration under the above conditions, the stability of the device prepared using the coating liquid. It is preferable in terms. That is, when the coating liquid is prepared in the air, there is a possibility that carbon dioxide in the air is also introduced 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 introduced into the coating solution will also be very low, but there have been no cases of measuring the dissolved carbon dioxide concentration in the coating solution so far. not. Also, there is no researched knowledge about its effect. In the present invention, compared to the concentration in the coating liquid of nitrogen and oxygen, which are the main components in the atmosphere, the concentration of carbon dioxide is actively created, and as a result, the effect of suppressing the introduction of oxygen or water into the coating liquid is expected. I did it.

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

It is preferable that the coating liquid of this invention is a coating liquid for electronic device manufacturing or ink jet ink.

The electronic device is preferably an organic EL device, a photoelectric conversion device (solar cell), or a light emitting device such as a liquid crystal display device.

(Organic compound)

The organic compound used in the present invention is not limited to a compound having a specific type or a specific structure, but a compound used in various electronic devices is preferable from the viewpoint of the effect of the present invention.

For example, when the coating liquid is a coating liquid for producing an organic EL device, it is preferable that the organic compound is an organic electroluminescent material (hereinafter, also referred to as "organic EL material"). The organic EL material refers to a compound that can be used for an organic electroluminescent layer (hereinafter also referred to as "organic functional layer" and "organic EL layer") formed between an anode and a cathode described later. In addition, a light-emitting element including an organic EL layer using these anodes, cathodes, and organic EL materials is referred to as an organic EL element. Examples of the compound used as the organic EL material will be described later.

In addition, when the coating liquid is a coating liquid for fabricating a photoelectric conversion element, it is preferable that the organic compound is a p-type organic semiconductor material or an n-type organic semiconductor material. Examples of the compounds used as these p-type organic semiconductor materials and n-type organic semiconductor materials will be described later.

(Organic solvent)

In the present invention, the organic solvent refers to a medium containing an organic compound capable of dissolving the organic compound according to the present invention.

As a liquid medium for dissolving or dispersing the organic EL device material according to the present invention, ketones such as methylene chloride, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone, fatty acid esters such as ethyl acetate, isopropyl acetate, and isobutyl acetate , Halogenated hydrocarbons such as chlorobenzene, dichlorobenzene, 2,2,3,3-tetrafluoro-1-propanol (TFPO), aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, cyclohexane, Aliphatic hydrocarbons such as decalin and dodecane, n-butanol, s-butanol, t-butanol alcohols, organic solvents such as DMF and DMSO, etc., in terms of suppressing the amount of solvent contained in the device, the boiling point A solvent in the range of 50 to 180°C is preferred.

[Method of preparing coating solution]

The manufacturing method of the 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 process, it is preferable to prepare the coating liquid using a solution containing the organic compound.

In addition, the method for preparing a coating solution of the present invention is a process of separating substances (e.g., water, oxygen, and organic compounds) in a solution containing the organic compound using a supercritical fluid (hereinafter, also referred to as a separation process). It is preferable to have ).

The mixing step is a step of mixing an organic compound and carbon dioxide. Specifically, carbon dioxide can be dissolved in an organic compound, for example, by bubbling carbon dioxide gas in a solution of an organic solvent and an organic compound to mix the organic compound and carbon dioxide, or a supercritical fluid chromatography method. And mixing organic compounds and carbon dioxide by using.

As for the bubbling of the carbonic acid gas, for example, it is preferable to bubble the high-purity carbonic acid gas for 1 to 60 minutes within a flow rate of 0.01 to 100 ml/min.

The coating solution of the present invention can be prepared by using the solution obtained by bubbling carbon dioxide gas as described above, that is, the organic solvent and the organic compound in which carbon dioxide is mixed by the mixing process. That is, the solution obtained by the mixing process can be used as it is as the coating liquid of the present invention.

The supercritical fluid chromatography method may use a packed column, an open column, or a capillary column.

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, and an organic compound to be separated if necessary. A device comprising an injector 14 for injecting, and a separation column 15, also a detector 17, and a pressure regulating valve 18, if necessary, may be used. The column 15 is temperature controlled in the column oven 16. As the filler, silica used in a conventional chromatography method, a surface-modified silica, or the like can be appropriately selected.

As described above, it is preferable that the method for producing the coating liquid of the present invention has a step (separation step) of separating the 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 prepared using a solution containing the separated organic compound and an organic solvent (including carbon dioxide). That is, the solution obtained by the mixing process can be used as it is as the coating liquid of the present invention.

In the present invention, the supercritical fluid refers to a substance in a supercritical state.

Here, the supercritical state will be described. Matter changes between three states: gas, liquid, and solid according to changes in environmental conditions such as temperature, pressure (or volume), and this is determined by the balance of intermolecular force and kinetic energy. It is called a phase diagram (phase diagram) that shows the transition of the three states of gas/liquid/solid by taking temperature on the horizontal axis and pressure on the vertical axis. A point that is present is called a 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, and is expressed as an evaporation curve (vapor pressure line). At a pressure lower than the pressure indicated by this curve, all the liquid is vaporized, and when a pressure higher than this is applied, all the vapor is liquefied. Even if the pressure is kept constant and the temperature is changed, if 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 in a state where there is no distinction between liquid and vapor, the interface between gas and liquid is also lost.

In a state higher than the critical point, it may change between liquid and gas without creating a gas-liquid coexistence state.

A fluid above the critical temperature and above the critical pressure is referred to as a supercritical fluid, and a temperature/pressure region providing the supercritical fluid is referred to as a supercritical region. A supercritical fluid can be understood as a high-density fluid having a high kinetic energy, and exhibits a liquid behavior in terms of dissolving a solute and a gaseous characteristic in terms of density variability. The supercritical fluid has various solvent properties, but it is an important property that it has low viscosity, high diffusion, and excellent permeability to solid materials.

The supercritical state is, for example, carbon dioxide, the critical temperature (hereinafter referred to as Tc) 31°C, the critical pressure (hereinafter 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 range, the fluid has a large diffusion coefficient and has a low viscosity, so mass transfer and concentration equilibrium are fast, In addition, since it has a high density like a liquid, efficient separation becomes possible. In addition, by using a substance that becomes a gas at normal pressure and room temperature such as carbon dioxide, recovery is quick. In addition, there are no various obstacles due to the inevitable residual amount of a solvent 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, but among these, carbon dioxide can be preferably used. have.

One type of solvent used as the supercritical fluid can be used alone, and a so-called modifier or entrainer can be added to adjust the polarity.

Examples of entrainers include hydrocarbon solvents such as hexane, cyclohexane, benzene, and toluene, halogenated hydrocarbon solvents such as methyl chloride, dichloromethane, dichloroethane, and chlorobenzene, and alcohols such as methanol, ethanol, propanol, and butanol. Solvents, ether solvents such as diethyl ether, tetrahydrofuran, acetal solvents such as acetoaldehyde diethyl acetal, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate and butyl acetate, formic acid, Carboxylic acid solvents such as acetic acid and trifluoroacetic acid, nitrogen compound solvents such as acetonitrile, pyridine, and N,N-dimethylformamide, sulfur compound solvents such as carbon disulfide and dimethyl sulfoxide, and water, nitric acid, Sulfuric acid and the like.

The use 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 is dissolved, but if the temperature is too low, the solubility of the organic compound in the supercritical fluid may be insufficient, and the temperature When is too high, the organic compound may be decomposed, so the use temperature range is preferably 20 to 600°C.

The working pressure of the supercritical fluid is not particularly limited as long as it is basically higher than the critical pressure of the substance used, but if the pressure is too low, the solubility of the organic compound in the supercritical fluid may be insufficient, and if the pressure is too high, it is manufactured. Since problems may arise in terms of durability of the device, safety during operation, etc., the working pressure is preferably 1 to 100 MPa.

A device using a supercritical fluid is not limited at all as long as it has a function of dissolving an organic compound into the supercritical fluid by contacting the supercritical fluid, and for example, a batch method using a supercritical fluid in a closed system, a supercritical fluid. It is possible to use a distribution method in which a critical fluid is circulated and a complex method in which a batch method and a distribution method are combined.

[Inks for electronic device manufacturing]

The ink for electronic device production of the present invention is characterized by containing the coating liquid. That is, the ink for electronic device production of the present invention is characterized in that it is derived from the coating liquid.

The electronic device is preferably a light emitting device, and further preferably an organic EL device or a photoelectric conversion device.

Each layer constituting the electronic device can be formed by the ink jet method using the ink for electronic device production 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 formed by coating the coating liquid.

The electronic device is preferably a light-emitting device, and further, an organic EL element or a photoelectric conversion element is preferable.

[Organic EL device]

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.

Hereinafter, the details of the organic EL device will be described.

As described above, the organic EL device of the present invention has a structure in which an anode and a cathode, and one or more organic functional layers (also referred to as ``organic compound layer'' and ``organic EL layer'') are sandwiched on a substrate on a substrate. .

(Board)

The substrate that can be used for the organic EL device of the present invention is not particularly limited, but a glass substrate, a plastic substrate, or the like can be used, and may be transparent or opaque. When light is extracted from the substrate side, it is preferable that the substrate is transparent. Glass, quartz, and transparent plastic substrates are mentioned as a transparent substrate preferably used. In addition, as a substrate, in a test conforming to JIS Z-0208, in order to prevent intrusion of oxygen or water from the substrate side, the thickness is 1 μm or more, and the water vapor transmission rate is 1 g/(m 2 ·24 h·atm) 25°C) or less.

Specifically as a glass substrate, an alkali free glass, a low alkali glass, a soda-lime glass, etc. are mentioned, for example. Among these, alkali-free glass is preferable from the viewpoint of little adsorption of moisture, but any of these may be used as long as it is sufficiently dried.

Plastic substrates are attracting attention in recent years for reasons such as high flexibility, light weight, and hard to crack, and the ability to further reduce the thickness of an organic EL element.

The resin film used as a substrate for a plastic substrate is not particularly limited, and for example, polyester such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose tree Cellulose esters such as acetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate, and cellulose nitrate, or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic Polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide, polyethersulfone (PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, poly Amide, fluorine resin, nylon, polymethyl methacrylate, acrylic or polyarylate, organic-inorganic hybrid resin, and the like.

Examples of the organic-inorganic hybrid resin include those obtained by combining an organic resin with an inorganic polymer (eg, silica, alumina, titania, zirconia, etc.) obtained by a sol-gel reaction. Among these, a norbornene (or cycloolefin type) resin such as Atone (manufactured by JSR Corporation) or Arpel (manufactured by Mitsui Chemical Corporation) is particularly preferable.

Plastic substrates normally produced have relatively high moisture permeability, and may contain moisture in the substrate. Therefore, when using such a plastic substrate, it is preferable to provide a film (hereinafter referred to as "barrier film" or "water vapor sealing film") for suppressing intrusion of water vapor or oxygen on the resin film.

The material constituting the barrier film is not particularly limited, and a film of an inorganic substance or an organic substance, or a hybrid of both is used. A barrier film having a water vapor permeability (25±0.5°C, relative humidity (90±2)% RH) of 0.01 g/(m²·24h) or less, measured by a method in accordance with JIS K 7129-1992, which may have a film formed thereon. It is preferable that the oxygen permeability measured by the method in accordance with JIS K 7126-1987 is 1×10 ^-3 mL/(㎡·24h·atm) or less, and the water vapor transmission rate is 1×10 ^-5 g/(㎡· It is preferable that it is a high barrier film which is less than 24h)

The material constituting the barrier film is not particularly limited as long as it has a function of suppressing the intrusion of moisture or oxygen that causes deterioration of the device. For example, inorganic substances such as metal oxides, metal oxynitrides or metal nitrides, organic substances, Alternatively, a hybrid material or the like of both can be used.

Examples of metal oxides, metal oxynitrides or metal nitrides include silicon oxide, titanium oxide, indium oxide, tin oxide, metal oxides such as indium tin oxide (ITO), aluminum oxide, metal nitrides such as silicon nitride, silicon oxynitride, and titanium oxynitride. And other metal oxynitrides.

In addition, in order to improve the fragility of the film, it is more preferable to provide a laminated structure of a layer containing these inorganic layers and organic materials. Although there is no restriction|limiting in particular about the lamination order of an inorganic layer and an organic layer, It is preferable that both are laminated|stacked alternately multiple times.

The barrier film is preferably a barrier film having a water vapor permeability (25±0.5°C, relative humidity (90±2)% RH) of 0.01 g/(m 2 ·24 h) or less measured by a method in accordance with JIS K 7129-1992. Furthermore, a highly barrier film with an oxygen permeability of 10 ^-3 mL/(m²·24h·atm or less) and a water vapor transmittance of 10 ^-5 g/(m²·24h) or less measured by a method in accordance with JIS K 7126-1987 It is preferable to be

The method of providing the barrier film on the resin film is not particularly limited, and any method may be used, but for example, vacuum 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, and the like can be used. Among these, a method by plasma CVD treatment at atmospheric pressure or near atmospheric pressure is preferable from the viewpoint of being able to form a dense film.

Examples of the opaque substrate include a metal plate such as aluminum and stainless steel, a film or an 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 alloy, an electrically conductive compound of a metal, or a mixture thereof is preferably used as an electrode material. Here, the "electrically conductive compound of a metal" refers to a compound of a metal and other substances having electrical conductivity, specifically, for example, an oxide or a halide of a metal, and refers to a compound having electrical conductivity.

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

In addition, a pattern of a desired shape may be formed on this thin film by a photolithography method, and when pattern precision is not very much required (about 100 μm or more), a mask of a desired shape may be used during deposition or sputtering of the electrode material. You may form a pattern by interposing.

In the case of extracting light from the anode, it is preferable to make the transmittance greater than 10%. In addition, sheet resistance as an anode is several hundred Ω/sq. The following are preferable. In addition, although the film thickness of the anode varies depending on the material constituting it, it 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'' and ``organic compound layer'') includes at least a light-emitting layer, and in a broad sense, the light-emitting layer refers to a layer that emits light when a current is passed through an electrode including a cathode and an anode. Denotes a layer containing an organic compound that emits light when a current is passed through an electrode including 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 take a structure in which these layers are sandwiched between a cathode and an anode.

Specifically,

(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

And the like.

In addition, a cathode buffer layer (eg, lithium fluoride) may be inserted between the electron injection layer and the cathode, or an anode buffer layer (eg, copper phthalocyanine) may be inserted between the anode and the hole injection layer.

(Luminescent layer)

The light-emitting layer according to the present invention is a layer that emits light by recombining electrons and holes injected from an electrode, an electron transport layer, or a hole transport layer, and a portion that emits light may be in the layer of the light-emitting layer or the interface between the light-emitting layer and the adjacent layer. The light-emitting layer may be a layer having a single composition or a laminated structure including a plurality of layers having the same or different composition.

Functions, such as a hole injection layer, an electron injection layer, a hole transport layer, and an electron transport layer, may be given to this light emitting layer itself. That is, (1) when an electric field is applied to the light emitting layer, holes can be injected by the anode or the hole injection layer, and an injection function capable of injecting electrons from the cathode or the electron injection layer, (2) the injected charge (electron And holes) by the force of an electric field, and (3) a light emitting function of providing a recombination site of electrons and holes in the light emitting layer and connecting them to light emission. In addition, the light-emitting layer may have a difference in the ease of injection of holes and the ease of injection of electrons, and may have a large or small transport function represented by the mobility of holes and electrons, but preferably has a function of moving at least one of the charges. Do.

There is no restriction|limiting in particular about the kind of the light-emitting material used for this light-emitting layer, What is conventionally known as a light-emitting material in an organic EL element can be used. Such light-emitting materials are mainly organic compounds, and depending on the desired color tone, for example, literature [Macromol. Symp. 125, pages 17 to 26]. Further, the light-emitting material may be a polymer material such as p-polyphenylene vinylene or polyfluorene, and a polymer material in which the light-emitting material is introduced into the side chain or a polymer material in which the light-emitting material is the main chain of the polymer may be used. . Further, 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 material or electron injection material described later can also be used as the light emitting material.

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

There are two types of dopants used for the light-emitting layer: a fluorescent dopant that emits fluorescence and a phosphorescent dopant that emits phosphorescence.

Representative examples of the fluorescent dopant include a coumarin-based dye, a pyran-based dye, a cyanine-based dye, a chromonium-based dye, a squarylium-based dye, an oxobenzanthracene-based dye, a fluorescein-based dye, a rhodamine-based dye, a pyryllium-based dye, and perylene-based dye , A stilbene-based dye, a polythiophene-based dye, or a rare earth complex fluorescent substance, 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 triplet is observed, and a phosphorescence quantum yield is 0.001 or more at 25°C. Phosphorescence quantum yield is preferably 0.01 or more, more preferably 0.1 or more. The phosphorescence quantum yield can be measured by the method described on page 398 (Maruzen, 1992 edition) of Spectroscopy II of the fourth edition experimental chemistry lecture 7. The phosphorescence quantum yield in a solution can be measured using various solvents, but the phosphorescent compound used in the present invention may achieve the phosphorescence quantum yield in any of any solvents.

The phosphorescent dopant is a phosphorescent compound, and a representative example thereof is preferably a complex system compound containing a metal of Group 8 to 10 in the periodic table of the elements, more preferably an iridium compound, an osmium compound, a rhodium compound, a palladium compound, Or a platinum compound (platinum complex system compound), and among them, an iridium compound, a rhodium compound, and a platinum compound are preferable, and an iridium compound is most preferable.

As an example of a dopant, it is a compound described in the following literature or patent publication. Literature [J. Am. Chem. Soc. 123 pages 4304 to 4312], International Publication No. 2000/70655, International Publication No. 2001/93642, International Publication No. 2002/02714, International Publication No. 2002/15645, International Publication No. 2002/44189, International Publication 2002/081488, Japanese Patent Application Publication No. 2002-280178, Japanese Patent Application Publication No. 2001-181616, Japanese Patent Application Publication No. 2002-280179, Japanese Patent Application Publication No. 2001-181617, Japanese Patent Application Publication No. 2002-280180, Japanese Patent Publication No. 2001-247859, Japanese Patent Publication No. 2002-299060, Japanese Patent Publication No. 2001-313178, Japanese Patent Publication No. 2002-302671, Japanese Patent Publication No. 2001-345183, JP 2002-324679, JP 2002-332291, JP 2002-50484, JP 2002-332292, JP 2002-83684, Japanese Patent Publication No. 2002-540572, Japanese Patent Publication No. 2002-117978, Japanese Patent Publication No. 2002-338588, Japanese Patent Publication No. 2002-170684, Japanese Patent Publication No. 2002-352960, Japanese Patent Application No. 2002-50483, Japanese Patent Application No. 2002-100476, Japanese Patent Application No. 2002-173674, Japanese Patent Application No. 2002-359082, Japanese Patent Application Publication No. 2002-175884, JP 2002-363552, JP 2002-184582, JP 2003-7469, JP 2002-525808, JP 2003-7471, Japanese Patent Publication No. 2002-525833, Japanese Patent Publication No. 2003-31366, Japan Japanese Patent Application Publication No. 2002-226495, Japanese Patent Application Publication No. 2002-234894, Japanese Patent Application Publication No. 2002-235076, Japanese Patent Application Publication No. 2002-241751, Japanese Patent Application Publication No. 2001-319779, Japan Patent Application Publication No. 2001-319780, Japanese Patent Application Publication No. 2002-62824, Japanese Patent Application Publication No. 2002-100474, Japanese Patent Application Publication No. 2002-203679, Japanese Patent Application Publication No. 2002-343572, Japan Patent Publication No. 2002-203678, etc.

Specific examples of the phosphorescent dopant 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 emission from these dopants, a light-emitting element having a plurality of maximum 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 stacked to form an organic EL device, the light-emitting dopants contained in each layer may be the same or different, and may be a single type or a plurality of types.

Further, the light-emitting dopant may be introduced into a polymer chain, or a polymer material having the light-emitting dopant as a main chain of the 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, as described below. An electron transport material and a hole transport material are also mentioned as corresponding examples. When applied to a blue or white light-emitting device, a display device, and a lighting device, the maximum fluorescence wavelength of the host compound is preferably 415 nm or less, and when a phosphorescent dopant is used, the 0-0 band of phosphorescence of the host compound is 450 nm. It is more preferable that it is the following. As the light-emitting host, a compound having a hole-transporting ability and an electron-transporting ability, further preventing a long wavelength of light emission, and further has a high Tg (glass transition temperature) is preferable.

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

Japanese Patent Application Publication No. 2001-257076, Japanese Patent Application Publication No. 2002-308855, Japanese Patent Application Publication No. 2001-313179, Japanese Patent Application Publication No. 2002-319491, Japanese Patent Application Publication No. 2001-357977, Japanese Patent Application Publication No. 2002-334786, Japanese Patent Application Publication No. 2002-8860, Japanese Patent Application Publication No. 2002-334787, Japanese Patent Application Publication No. 2002-15871, Japanese Patent Application Publication No. 2002-334788, Japanese Patent Application Publication No. 2002-43056, Japanese Patent Application Publication No. 2002-334789, Japanese Patent Application Publication No. 2002-75645, Japanese Patent Application Publication No. 2002-338579, Japanese Patent Application Publication No. 2002-105445, Japanese Patent Application Publication No. 2002-343568, Japanese Patent Application Publication No. 2002-141173, Japanese Patent Application Publication No. 2002-352957, Japanese Patent Application Publication No. 2002-203683, Japanese Patent Application Publication No. 2002-363227, Japanese Patent Application Publication No. 2002-231453, Japanese Patent Application Publication No. 2003-3165, Japanese Patent Application Publication No. 2002-234888, Japanese Patent Application Publication No. 2003-27048, Japanese Patent Application Publication No. 2002-255934, Japanese Patent Application Publication No. 2002-260861, Japanese Patent Application Publication No. 2002-280183, Japanese Patent Application Publication No. 2002-299060, Japanese Patent Application Publication No. 2002-302516, Japanese Patent Application Publication No. 2002-305083, Japanese Unexamined Patent Publication No. 2002-305084, Japanese Unexamined Patent Publication No. 2002-308837, etc.

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

Using the above material, a light emitting layer can be formed by thinning by a known method such as evaporation, spin coating, cast, LB, inkjet transfer, and printing, but the formed light emitting layer is particularly It is preferably a sediment film. Here, the molecular deposition film refers to a thin film formed by being deposited from the gas phase state of the compound, or a film formed by solidifying from the molten state or liquid state of the compound. Usually, this molecular deposition film and a thin film (molecular accumulation film) formed by the LB method can be distinguished by a difference in an aggregated structure and a higher-order structure, or a functional difference resulting therefrom.

In the present invention, it is preferable to use the phosphorescent dopant and host compound as the light emitting material as the organic compound of the present invention. That is, it is preferable to form the light-emitting layer by coating a solution containing the phosphorescent dopant and host compound, and an organic solvent, such as spin coating, because a light-emitting layer containing a molecular volume film can be formed. And, in the coating liquid containing the phosphorescent dopant and the host compound, and an organic solvent, it is preferable that the dissolved carbon dioxide concentration in the organic solvent under atmospheric pressure conditions at 50° C. or lower is 1 ppm to the saturated concentration in the organic solvent. .

As a means for bringing the dissolved carbon dioxide concentration into the above range, as described above, a method of bubbling carbon dioxide gas in a solution containing a phosphorescent dopant and a host compound and an organic solvent, or a supercritical fluid containing an organic solvent and carbon dioxide The supercritical fluid chromatography method using is mentioned.

(Hole injection layer and hole transport layer)

The hole injection material used for the hole injection layer has either a hole injection or an electron barrier property. Further, the hole transport material used for the hole transport layer has an electron barrier property and an action of transporting holes to the light emitting layer. Therefore, in the present invention, the hole transport layer is included in the hole injection layer. These hole injection materials and hole transport materials may be either organic or inorganic. Specifically, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino substituted chalcone derivatives, oxazole derivatives , Conductive polymer oligomers such as styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, porphyrin compounds, and thiophene oligomers. Among these, arylamine derivatives and porphyrin compounds are preferable. Among the arylamine derivatives, aromatic tertiary amine compounds and styrylamine compounds are preferred, and aromatic tertiary amine compounds are more preferred.

Representative examples of the aromatic tertiary amine compound and styrylamine compound include 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-tolylaminophenyl)-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]stilbene; 4-N,N-diphenylamino-(2-diphenylvinyl)benzene; 3-methoxy-4'-N,N-diphenylaminostilbene; N-phenylcarbazole, furthermore having two condensed aromatic rings described in the specification of U.S. Patent No. 5061569 in a molecule, for example 4,4'-bis[N-(1-naphthyl)-N-phenyl Amino]biphenyl (hereinafter abbreviated as α-NPD), triphenylamine units described in Japanese Patent Laid-Open No. Hei 4-308688 4,4',4"-tris[ N-(3-methylphenyl)-N-phenylamino]triphenylamine (MTDATA), etc. In addition, inorganic compounds such as p-Si and p-SiC can also be used as the hole injection material.

In addition, in the present invention, it is preferable that the hole transport material of the hole transport layer has a maximum fluorescence wavelength of 415 nm or less. That is, the hole-transporting material is preferably a compound having a hole-transporting ability, preventing a longer wavelength of light emission, and further having a high Tg.

The hole injection layer and the hole transport layer include the hole injection material and the hole transport material by known methods such as vacuum evaporation, spin coating, cast, LB, inkjet, transfer, and printing, It can be formed by making it thin.

Further, in the present invention, it is preferable to use the hole injection material or hole transport material as the organic compound of the present invention. That is, it is preferable to form the hole transport layer (or hole injection layer) by coating a solution containing the hole transport material (or hole injection material) and an organic solvent by coating such as spin coating, and the hole transport material (or In the coating liquid containing a hole injection material) and an organic solvent, it is preferable to set the dissolved carbon dioxide concentration to the organic solvent under atmospheric pressure conditions at 50° C. or less to a saturation concentration of 1 ppm to the organic solvent.

As a means of making 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 transport material and an organic solvent, or a supercritical fluid containing an organic solvent and carbon dioxide is used. Critical fluid chromatography method is 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. In addition, the hole injection layer and the hole transport layer may have a single-layer structure each containing one or two or more of the above materials, or a laminated structure including a plurality of layers of the same composition or different composition. In addition, in the case of providing both the hole injection layer and the hole transport layer, among the above materials, different materials are usually used, but the same material may be used.

(Electron injection layer and electron transport layer)

The electron injection layer only needs to have a function of transferring electrons injected from the cathode to the light emitting layer, and as the material, any one of conventionally known compounds can be selected and used. Examples of the material used for the electron injection layer (hereinafter, also referred to as electron injection material) include heterocyclic tetracarboxylic anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, and naphthaleneperylene. , Carbodiimide, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like.

In addition, a series of electron-transmitting compounds described in Japanese Patent Laid-Open No. 59-194393 are disclosed as materials for forming a light-emitting layer in the publication, but as a result of the inventors' investigation, they can be used as electron injection materials. And it was found. Further, in the oxadiazole derivative, a thiadiazole derivative in which an oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as the electron injection material.

In addition, metal complexes of 8-quinolinol derivatives, for example, tris(8-quinolinol)aluminum (abbreviated as Alq ₃ ), tris(5,7-dichloro-8-quinolinol)aluminum, tris( 5,7-dibromo-8-quinolinol) aluminum, tris(2-methyl-8-quinolinol) aluminum, tris(5-methyl-8-quinolinol) aluminum, bis(8-quinolinol) Nol) zinc (Znq) or the like, and a metal complex in which the central metal of the metal complex thereof is substituted with 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 in which their terminals are substituted with an alkyl group or a sulfonic acid group, can be preferably used as the electron injection material. Further, like the hole injection layer, inorganic semiconductors such as n-Si and n-SiC can be used as the electron injection material.

It is preferable that a preferable compound used for the electron transport layer has a fluorescence maximum wavelength of 415 nm or less. That is, the compound used in the electron transport layer is preferably a compound having an electron transporting ability, preventing a longer wavelength of light emission, and further having a high Tg.

The electron injection layer can be formed by thinning the electron injection material by a known method such as a vacuum vapor deposition method, a spin coating method, a cast method, an LB method, an ink jet method, a transfer method, and a printing method.

Further, in the present invention, it is preferable to use the electron injection material as the organic compound of the present invention. That is, it is preferable to form the electron injection layer by coating a solution containing the electron injection material and the organic solvent, such as spin coating, and in the coating solution containing the electron injection material and the organic solvent, 50 It is preferable to set the dissolved carbon dioxide concentration in the organic solvent under atmospheric pressure conditions to 1 ppm to the saturated concentration in the organic solvent.

As a means of making the dissolved carbon dioxide concentration within 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 is used. Critical fluid chromatography method is mentioned.

In addition, the thickness as 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 single-layer structure including one type or two or more types of these electron injection materials, or may be a laminate structure including a plurality of layers of the same composition or different composition.

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

The electron transport layer is also called a hole blocking layer (hole blocking layer), and examples thereof include, for example, International Publication No. 2000/70655, Japanese Patent Laid-Open No. 2001-313178, Japanese Patent Laid-Open No. 11-204258, Japanese Patent Application Laid-Open No. 11-204359 and “Organic EL devices and their industrialization front lines (issued by NTS on Nov. 30, 1998)” on page 237 and the like. In particular, in a so-called "phosphorescent light emitting device" in which an orthometal complex dopant is used in the light emitting layer, it is preferable to have a configuration having an electron transport layer (hole blocking layer) as in the above (v) and (vi).

(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 refers to the layer provided between the electrode and the organic layer for lowering the driving voltage or improving the luminous efficiency, and Chapter 2 of the second part of ``Organic EL devices and their industrialization front lines (published by NTS on November 30, 1998)'' It is described in detail in "electrode material" (pages 123 to 166), and includes an anode buffer layer and a cathode buffer layer.

As for the anode buffer layer, the details are described in Japanese Patent Laid-Open No. 9-45479, Japanese Patent Laid-Open No. Hei 9-260062, Japanese Patent Laid-Open No. 8-288069, etc., and as a specific example, represented by copper phthalocyanine. And a phthalocyanine buffer layer, an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

The details of the cathode buffer layer are described in Japanese Patent Laid-Open No. Hei 6-325871, Japanese Patent Laid-Open No. 9-17574, Japanese Patent Laid-Open No. Hei 10-74586, and the like, specifically, strontium or aluminum. A typical metal 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 may be mentioned.

The buffer layer is preferably a very thin film, depending on the material, but the thickness is preferably in the range of 0.1 to 100 nm. Further, in addition to the basic constitution layer, layers having other functions may be appropriately laminated if necessary.

(cathode)

As described above, as the cathode of the organic EL device, in general, a metal having a small work function (less than 4 eV) (hereinafter referred to as an electron injecting metal), an alloy, an electrically conductive compound of metal, or a mixture thereof is used as an electrode material. Used.

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

In the present invention, the ones listed above may be used as the electrode material of the negative electrode, but from the viewpoint of more effectively exerting the effects of the present invention, the negative electrode is preferably made of a Group 13 metal element. That is, in the present invention, by oxidizing the surface of the cathode with oxygen gas in a plasma state as described later to form an oxide film on the surface of the cathode, further oxidation of the cathode can be prevented and durability of the cathode can be improved.

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

As the electrode material of the negative electrode containing the Group 13 metal element, specifically, for example, aluminum, indium, magnesium/aluminum mixture, magnesium/indium mixture, aluminum/aluminum oxide (Al ₂ O ₃ ) mixture, lithium/ And aluminum mixtures. In addition, the mixing ratio of each component of the mixture may be a conventionally known ratio as the cathode of the organic EL element, but is not particularly limited thereto. The cathode can be manufactured by forming a thin film on the organic compound layer (organic EL layer) by depositing the electrode material or sputtering the electrode material.

In addition, the sheet resistance as the cathode is several hundred Ω/sq. The following are preferable, and the film thickness is usually selected in the range of 10 nm to 1 µm, and preferably 50 to 200 nm. Further, in order to transmit the luminescent light, when either the anode or the cathode of the organic EL element is made transparent or semitransparent, the luminous efficiency is improved, and thus it is preferable.

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

[Method of manufacturing organic EL device]

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

First, on a suitable substrate, a thin film containing a desired electrode material, for example, a material for an anode, is formed to a thickness of 1 μm or less, preferably 10 to 200 nm, by a method such as vapor deposition or sputtering, and the anode is formed. Make it. Then, 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 device materials, is formed thereon.

As a method of thinning these organic compound thin films, as described above, there are spin coating method, cast method, inkjet method, vapor deposition method, printing method, etc., but it is easy to obtain a homogeneous film and it is difficult to generate pinholes. In this regard, a vacuum evaporation method or a spin coating method is preferable, and in the present invention, a spin coating method is particularly preferable in that the coating liquid of the present invention can be used.

Moreover, you may apply a different film formation method for each layer. In the case of employing a vapor deposition method for film formation, the vapor deposition conditions vary depending on the type of compound to be used, but in general, boat heating temperature is 50 to 450 copper, vacuum degree is 10 ^-6 to 10 ^-2 Pa, and deposition rate is 0.01 to 50 nm/sec. , It is preferable to appropriately select a substrate temperature in the range of -50 to 300°C and a thickness of 0.1 nm to 5 μm.

After forming these layers, a thin film containing a material for a cathode is formed thereon so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, by a method such as evaporation or sputtering, to form a cathode. By providing, a desired organic EL element is obtained. The organic EL device is preferably fabricated from the hole injection layer to the cathode consistently in one vacuum, but may be taken out in the middle to perform different film formation methods. At that time, consideration such as performing the operation in a dry inert gas atmosphere is required.

[Sealing of organic EL devices]

Although it does not specifically limit as a sealing means of an organic EL element, For example, after sealing the outer peripheral part of an organic EL element with a sealing adhesive, a method of arrange|positioning a sealing member so that the light emitting area of an organic EL element may be mentioned is mentioned.

Examples of the sealing adhesive include photocurable and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylic acid esters. Further, thermal and chemical curing types (two-liquid mixing) such as epoxy-based can be cited. Moreover, hot melt type polyamide, polyester, and polyolefin are mentioned. Further, a cationic curing type ultraviolet curable epoxy resin adhesive may be mentioned.

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

In the gap between the sealing member and the light emitting region of the organic EL element, in addition to the sealing adhesive, an inert gas such as nitrogen or argon in the gaseous and liquid phases, or an inert liquid such as fluorocarbon or silicone oil may be injected. Further, the gap between the sealing member and the display area of the organic EL element may be vacuumed, or a hygroscopic compound may be sealed in the gap.

[Display device]

In the multicolor display device using the organic EL device of the present invention, a shadow mask is provided only when the light emitting layer is formed, and the other layers are common, so patterning such as a shadow mask is unnecessary, and a vapor deposition method, a cast method, a spin coat method, etc. The film can be formed by an ink jet method or a printing method.

In the case of patterning only the light emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

In addition, it is also possible to manufacture in the order of a cathode, an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, a hole injection layer, and an anode by inverting the manufacturing 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 anode as + and the cathode as -. In addition, even when a voltage is applied with reverse polarity, no current flows and no light emission occurs. In addition, when an alternating voltage is applied, light is emitted only when the positive electrode becomes + and the negative electrode becomes -. In addition, 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 sources. In display devices and displays, full-color display becomes possible by using three types of organic EL elements of blue, red, and green light emission.

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

Examples of luminescent light sources include home lighting, in-vehicle lighting, backlight for clocks and liquid crystals, billboard advertisements, signal devices, light sources for optical storage media, light sources for electrophotographic copiers, light sources for optical communication processors, light sources for optical sensors, etc. It is not limited.

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

Examples of the use of the organic EL element having such a resonator structure include, but are not limited to, a light source for an optical storage medium, a light source for an electrophotographic copying machine, a light source for an optical communication processor, and a light source for an optical sensor. Moreover, by making laser oscillation, you may use for the said use.

The organic EL element of the present invention may be used as a type of lamp such as for illumination or exposure light source, and is used as a type of projection device that projects an image, or a type of display device (display) that directly visually recognizes a still image or moving image. Also works. When used as a display device for moving image reproduction, the driving method may be a simple matrix (passive matrix) system, an active matrix system, or either. Alternatively, it is possible to fabricate a full-color display device by using two or more types of the organic EL elements of the present invention having different luminous colors.

An example of a display device comprising the organic EL element of the present invention will be described below based on the drawings.

4 is a schematic diagram showing an example of a display device made of an organic EL element. It is a schematic diagram of a display such as a mobile phone, 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 for performing image scanning 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 the plurality of pixels based on image information from the outside, and transmits the pixel to the image data signal for each scanning line by the scanning signal. Accordingly, light is sequentially emitted to perform image scanning, and image information is displayed on the display unit A.

5 is a schematic diagram of the display portion A. The display portion A includes a wiring portion including a plurality of scan lines 55 and data lines 56, a plurality of pixels 53, and the like on a substrate. The main members of the display portion A will be described below.

In FIG. 5, the case where light emitted from the pixel 53 is extracted in the direction of the white arrow (downward direction) is shown. The scanning line 55 and the plurality of data lines 56 of the wiring unit each contain a conductive material, and the scanning line 55 and the data line 56 are orthogonal to the grid and connected to the pixel 53 at a position perpendicular to each other. (Details are 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 juxtaposing pixels in the red region, pixels in the green region, and pixels in the blue region whose emission colors are on the same substrate.

Next, the light emission process of the pixel will be described.

6 is a schematic diagram of a pixel. The pixel includes an organic EL element 60, a switching transistor 61, a driving transistor 62, a capacitor 63, and the like. Full-color display can be performed by using red, green, and blue light-emitting organic EL elements as the organic EL elements 60 for a plurality of pixels, and placing them on the same substrate.

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

By transmission of the image data signal, the capacitor 63 is charged according to the potential of the image data signal, and the driving transistor 62 is turned on. The driving transistor 62 has a drain connected to the power supply line 67, a source connected to an electrode of the organic EL element 60, and the power supply line 67 according to the potential of the image data signal applied to the gate. Current is supplied to the organic EL element 60.

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 when the driving of the switching transistor 61 is turned off, the capacitor 63 maintains the potential of the charged image data signal, so that the driving of the driving transistor 62 remains on, and when the next scanning signal is applied. Until, the light emission of the organic EL element 60 continues. By sequential scanning, when a scanning signal is next applied, the driving transistor 62 is driven in accordance with the potential of the image data signal and then in synchronization with the scanning signal, so that the organic EL element 60 emits light. In other words, the light emission of the organic EL element 60 is achieved by providing the switching transistor 61 and the driving transistor 62 as active elements for the organic EL element 60 of each of the plurality of pixels, and the plurality of pixels 53 (Not shown in Fig. 6, shown in Fig. 5) Each organic EL element 60 emits light. This light emission method is referred to as an active matrix method.

Here, the light emission of the organic EL element 60 may be light emission of a plurality of gray levels by a multi-valued image data signal having a plurality of gray level potentials, or a predetermined amount of light emission by a binary image data signal may be turned on or off.

In addition, the potential of the capacitor 63 may be maintained continuously until the application of the next scan signal, or may be discharged immediately before the next scan signal is applied.

In the present invention, it is not limited to the above-described active matrix method, but may be a passive matrix type light emission drive in which the organic EL element emits light in response to a data signal only when a scan signal is scanned.

7 is a schematic diagram of a display device using a passive matrix system. In FIG. 7, a plurality of scanning lines 55 and a plurality of image data lines 56 are provided in a grid shape to face each other with a pixel 53 interposed therebetween. When the scanning signal of the scanning line 55 is applied by sequential scanning, the pixel 53 connected to the applied scanning line 55 emits light in accordance with the image data signal. In the passive matrix system, there are no active elements in the pixel 53, and 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 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 forming a coating film of the coating liquid.

Hereinafter, the details of the photoelectric conversion element and the solar cell will be described.

8 is a cross-sectional view showing an example of a solar cell having a single configuration (a configuration in which a bulk heterojunction layer is one layer) including a bulk heterojunction type organic photoelectric conversion element.

In FIG. 8, the bulk heterojunction type organic photoelectric conversion element 200 is photoelectric conversion of a transparent electrode (anode) 202, a hole transport layer 207, and a bulk heterojunction layer on one side of the substrate 201. A portion 204, an electron transport layer (also referred to as a buffer layer) 208, and a counter electrode (cathode) 203 are sequentially stacked.

The substrate 201 is a member that holds the transparent electrode 202, the photoelectric conversion unit 204, and the counter electrode 203 sequentially stacked. In this embodiment, since the light to be photoelectrically converted from the side of the substrate 201 is incident, the substrate 201 is a member capable of transmitting the photoelectrically converted light, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. desirable. As the substrate 201, for example, a glass substrate, a resin substrate, or the like is used. This substrate 201 is not essential, and for example, by forming the transparent electrode 202 and the counter electrode 203 on both sides of the photoelectric conversion unit 204, even if the bulk heterojunction type organic photoelectric conversion element 200 is configured. do.

The photoelectric conversion unit 204 is a layer that converts light energy into electrical energy, and is configured with 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 relatively functions as an electron donor (donor), and the n-type semiconductor material relatively functions as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are "an electron donor and an electron acceptor that when absorbing light, electrons move from the electron donor to the electron acceptor and form a pair of holes and electrons (charge separation state)", and Likewise, it is not simply donating or accepting electrons, but donating or accepting electrons through photoreaction.

In Fig. 8, light incident from the transparent electrode 202 through 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 the electron acceptor from the electron donor. As electrons move, pairs of holes and electrons (charge separation state) are formed. The generated charge is an internal electric field, for example, when the work functions of the transparent electrode 202 and the counter electrode 203 are different, due to the potential difference between the transparent electrode 202 and the counter electrode 203, electrons pass between the electron acceptors. In addition, the holes pass through the electron donors and are transported to different electrodes, respectively, so that a photocurrent is detected. 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. In addition, when the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction to this. Further, by applying a potential between the transparent electrode 202 and the counter electrode 203, the transport direction of electrons and holes can also be controlled.

In addition, although not described in FIG. 8, other layers, such as a hole blocking layer, an electron blocking 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 light utilization rate (photoelectric conversion efficiency), a tandem configuration in which such photoelectric conversion elements are stacked (a configuration having a plurality of bulk heterojunction layers) may be used.

9 is a cross-sectional view showing a solar cell including an organic photoelectric conversion element having a tandem bulk heterojunction layer. In the case of a tandem configuration, after sequentially stacking the transparent electrode 202 and the first photoelectric conversion unit 209 on the substrate 201, the charge recombination layer (intermediate electrode) 205 is stacked, and then the second photoelectric By laminating the conversion section 206 and then the counter electrode 203, a tandem configuration can be obtained.

As for the material that can be used for such a layer, the n-type semiconductor material and the p-type semiconductor material described in paragraphs 0045 to 0113 of Japanese Unexamined Patent Application Publication No. 2015-149483 are mentioned, for example.

(Method of forming bulk heterojunction layer)

As a method of forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed, a vapor deposition method, a coating method (including a cast method and a spin coating method) can be exemplified. Among these, in order to increase the area of the interface at which the above-described holes and electrons are separated by charge, and to manufacture a device having high photoelectric conversion efficiency, a coating method is preferable. In addition, the coating method is also excellent in manufacturing speed.

In the present invention, an n-type semiconductor material and a 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 to form a bulk heterojunction layer by coating a solution containing the n-type semiconductor material and the p-type semiconductor material and an organic solvent, and the n-type semiconductor material and the p-type semiconductor material and the organic In the coating liquid containing a solvent, it is preferable to set the dissolved carbon dioxide concentration to the organic solvent under atmospheric pressure conditions at 50°C or less to be 1 ppm to the saturated concentration to the organic solvent.

As a means of making 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 containing an organic solvent and carbon dioxide. And a supercritical fluid chromatography method using a supercritical fluid.

After application, it is preferable to perform heating in order to remove residual solvent, moisture, and gas, and improve mobility due to crystallization of the semiconductor material and increase absorption length. When annealing treatment is performed at a predetermined temperature during the manufacturing process, the arrangement or crystallization of a part microscopically is promoted, so that 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, or may be composed of a plurality of layers in which the mixing ratio of the electron acceptor and the electron donor is changed.

Next, an electrode constituting the organic photoelectric conversion element will be described.

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

(The opposite pole)

In the present invention, the counter electrode (cathode) is preferably an electrode that extracts electrons. For example, in the case of using as a negative electrode, a single layer of a conductive material may be sufficient, but in addition to a material having conductivity, a resin holding them may be used in combination.

As the counter electrode material, known negative electrode conductive materials described in Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, and the like can be used, for example.

As the counter electrode material, known negative electrode conductive materials described in Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, and the like can be used, for example.

(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, known materials for cathodes described in Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, and the like can be used, for example.

(Intermediate electrode)

Further, as a material for the intermediate electrode required in the case of a tandem configuration, it is preferable that it is a layer using a compound having both transparency and conductivity.

As the material, known materials for intermediate electrodes described in JP 2010-272619 A, JP 2014-078742 A, and the like can be used.

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

(Hole transport layer and electron block layer)

The organic photoelectric conversion device of the present invention preferably has a hole transport layer and an electron block layer between the bulk heterojunction layer and the transparent electrode in order to enable more efficient extraction of charges generated in the bulk heterojunction layer. .

As the material for photoelectric conversion elements constituting the hole transport layer, known materials described in Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, or the like can be used.

(Electron transport layer, hole block layer, and buffer layer)

In the organic photoelectric conversion element of the present invention, by forming an electron transport layer, a hole block layer, and a buffer layer between the bulk heterojunction layer and the counter electrode, it becomes possible to more efficiently extract the charges generated in the bulk heterojunction layer. It is preferable to have.

In addition, as the electron transport layer, for example, known materials described in JP 2010-272619 A, JP 2014-078742 A, or the like can be used. The electron transport layer may be a hole blocking layer to which a hole blocking function is imparted, which has a rectifying effect that does not flow holes generated in the bulk heterojunction layer to the counter electrode side. As the material for forming the hole blocking layer, for example, a known material described in JP 2014-078742 A can be used.

(Other floors)

For the purpose of improving energy conversion efficiency or improving device life, various intermediate layers may be included in the device. Examples of the intermediate layer include a hole blocking layer, an electron blocking layer, a hole injection layer, an electron injection layer, an exciton blocking layer, a UV absorbing layer, a light reflection layer, and a wavelength conversion layer.

(Board)

When light to be photoelectrically converted from the substrate side enters, the substrate is preferably a member capable of transmitting the photoelectrically converted light, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. As the substrate, for example, a glass substrate, a resin substrate, or the like can be suitably mentioned, but it is preferable to use a transparent resin film from the viewpoint of light weight and flexibility.

There is no particular limitation on the transparent resin film that can be preferably used as a transparent substrate in the present invention, and the material, shape, structure, thickness, and the like can be appropriately selected from known ones. For example, known materials described in JP 2010-272619 A, JP 2014-078742 A, 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 more efficient light reception of sunlight. As the optical functional layer, for example, an antireflection film, a light collecting layer such as a microlens array, a light diffusion layer capable of scattering the light reflected from the counter electrode and causing it to be incident on the bulk heterojunction layer may be provided.

As the antireflection layer, the light collecting layer, and the light scattering layer, for example, known antireflection layers, light collecting layers and light scattering layers described in Japanese Patent Application Laid-Open No. 2010-272619, Japanese Patent Application Laid-Open No. 2014-078742 and the like can be used, respectively.

(Patterning)

There is no particular limitation on the method or process of patterning the electrode, the power generation layer, the hole transport layer, the electron transport layer and the like according to the present invention, and for example, Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, etc. The disclosed known methods can be appropriately applied.

(Sealed)

In addition, in order to prevent the fabricated organic photoelectric conversion element from deteriorating due to oxygen, moisture, or the like in the environment, it is preferable to seal not only the organic photoelectric conversion element but also an organic electroluminescent element by a known method. For example, the method described in Japanese Patent Laid-Open No. 2010-272619, Japanese Patent Laid-Open No. 2014-078742, or the like can be used.

<Example>

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, in the examples shown below, dry air refers to dry air produced using a dry air generating device (manufactured by Ikeda Rika, AT35HS), and the atmospheric condition is set to 25°C and 1 atm. The expression under the atmosphere and under the nitrogen atmosphere refers to under a nitrogen atmosphere using nitrogen gas supplied from a nitrogen cylinder made by Taiyo Nissan G1 grade.

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

[Example 1]

To a solution (s-1) in which 5 g of CBP was dissolved in 1 L of toluene (Kanto Chemical Co., Ltd., dehydrated toluene) in a high-purity nitrogen atmosphere, high-purity carbon dioxide gas (Taiyo Nissan, high-purity carbon dioxide gas (>99.995 vol.%) was added to the solution (s-1). After bubbling for 10 minutes at a flow rate of 100 mL/min, a solution s-5 was prepared by degassing for 10 minutes.

The amount of carbon dioxide contained in s-1 and s-5 was measured by gas chromatography. Specifically, Porapack Type S GC Bulk Packing Material (Mesh80-100) manufactured by Waters Corporation was used as the column filler, and it was measured by an absolute calibration curve method.

In addition, the water content of s-1 and s-5 were measured by the Karl Fischer method. Table 1 shows each result.

In addition, the various solvents shown in Table 1 were subjected to the same treatment, and the various solvents were not bubbled with high-purity carbon dioxide gas (s-2 to s-4), and those that were bubbled (s-6 to s). -8) was prepared, and the amount of carbon dioxide and water content of s-2 to s-4 and s-6 to s-8 were measured. The results are shown in Table 1.

In addition, various solvents used are as follows.

Toluene (Kanto Chemical Co., Ltd., dehydrated toluene), Isobutyl acetate (Kanto Chemical Co., Ltd., special grade isobutyl acetate), TFPO (Tokyo Kasei Kogyo Co., Ltd., 2,2,3,3-tetrafluoro -1-propanol)

From the results shown in Table 1, it can be seen that by mixing carbon dioxide with various solvents, the water content in various solvents could be reduced.

[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. Table 2 shows each result.

From the results shown in Table 2, it can be seen that the introduction of oxygen in the organic solvent containing carbon dioxide is small when stored in dry air and atmosphere.

[Example 3]

After patterning was performed on a substrate (NA45 manufactured by NH Techno Glass) on which 100 nm of ITO (indium tin oxide) was formed on a glass substrate of 100 mm×100 mm×1.1 mm, the transparent support substrate provided with this ITO transparent electrode was prepared with isopropyl alcohol. Ultrasonic cleaning, drying with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. On this substrate, s-4 produced in Example 1 was formed into a film by an ink jet method (film thickness of about 40 nm), and the mass (w(0)) before the start of drying was measured. Thereafter, the mass (w(t)) when dried at 60° C. for t minutes and the mass (w(60)) when dried under vacuum 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 (w(t)) after drying for t minutes, the degree of drying after drying for t minutes (Dry( 101)) was obtained by the following equation.

Dry101(t)=(1-((w(t)-w(60))/(w(0)-w(60)))×100

s-4 was substituted with the other solutions shown in Table 3, and the same measurement was performed, and the result of Table 3 was obtained.

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

[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 method, respectively, and one was referred to as solution s-11. , And the other side was bubbled with carbon dioxide for 10 minutes in a glove box under a nitrogen atmosphere, and was called solution s-12. The carbon dioxide concentration of solution s-12 was measured by the method of Example 1, and it was confirmed that it contained 200 ppm of carbon dioxide. In addition, the solution s-11 and the solution s-12 were divided into 3 portions, respectively, and treated by the following method to obtain a solution shown in Table 4.

Treatment 1: Solution s-11 was prepared and stored for 30 minutes in a nitrogen atmosphere to obtain solution s-111.

Treatment 2: Solution s-11 was stored for 30 minutes in a dry air atmosphere to obtain solution s-112.

Treatment 3: Solution s-11 was stored for 30 minutes under the atmosphere, and solution s-113 was obtained.

Treatment 4: The solution s-12 was stored for 30 minutes under a nitrogen atmosphere prepared to obtain a solution s-121.

Treatment 5: Solution s-12 was stored for 30 minutes in a dry air atmosphere to obtain solution s-122.

Treatment 6: Solution s-12 was stored for 30 minutes under the atmosphere, and solution s-123 was obtained.

<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 the compound Ir-12 were dissolved in 60 ml of toluene/isobutyl acetate (1/1) was divided into two, and treated by the following method. , One side was referred to as solution s-21, and the other was referred to as solution s-22 by bubbling carbon dioxide for 10 minutes in a glove box under a nitrogen atmosphere. The carbon dioxide concentration of solution s-22 was measured by the method of Example 1, and it was confirmed that it contained 250 ppm of carbon dioxide. Further, the solution s-21 and the solution s-22 were divided into three, respectively, and treated by the following method to obtain a solution shown in Table 4.

Treatment 11: The solution s-21 was prepared and stored for 30 minutes under a nitrogen atmosphere to obtain a solution s-211.

Treatment 12: Solution s-21 was stored for 30 minutes in a dry air atmosphere to obtain solution s-212.

Treatment 13: The solution s-21 was stored for 30 minutes under the atmosphere to obtain a solution s-213.

Treatment 14: Solution s-22 was prepared and stored for 30 minutes under a nitrogen atmosphere to obtain solution s-221.

Treatment 15: Solution s-22 was stored for 30 minutes in a dry air atmosphere to obtain solution s-222.

Treatment 16: Solution s-22 was stored for 30 minutes under the atmosphere to obtain 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 and treated by the following method, respectively, and one was referred to as solution s-31. , And the other side was bubbled with carbon dioxide for 10 minutes in a glove box under a nitrogen atmosphere, and was referred to as solution s-32. The carbon dioxide concentration of solution s-32 was measured by the method of Example 1, and it was confirmed that it contained 180 ppm of carbon dioxide. In addition, the solution s-31 and the solution s-32 were divided into three, respectively, and treated by the following method to obtain a solution shown in Table 4.

Treatment 21: Solution s-31 was prepared and stored for 30 minutes under a nitrogen atmosphere to obtain solution s-311.

Treatment 22: Solution s-31 was stored for 30 minutes in a dry air atmosphere to obtain solution s-312.

Treatment 23: The solution s-31 was stored for 30 minutes in the atmosphere to obtain a solution s-313.

Treatment 24: Solution s-32 was prepared and stored for 30 minutes under a nitrogen atmosphere to obtain solution s-321.

Treatment 25: Solution s-32 was stored for 30 minutes in a dry air atmosphere to obtain solution s-322.

Treatment 26: The solution s-32 was stored for 30 minutes under the atmosphere to obtain a solution s-323.

<Production of organic EL device>

After patterning was performed on a substrate (NA45 manufactured by NH Techno Glass) on which 100 nm of ITO (indium tin oxide) was formed on a 100 mm×100 mm×1.1 mm glass substrate as an anode, the transparent support substrate provided with this ITO transparent electrode was isopropyl. It ultrasonically washed with alcohol, dried with dry nitrogen gas, and UV ozone washing was performed for 5 minutes. This substrate was installed on a commercially available spin coater, spin-coated under the conditions of 1000 rpm and 30 seconds using solution s-111 (10 ml) (layer thickness: about 40 nm), vacuum dried at 60° C. for 1 hour, and holes It was set as the transport layer. Next, using the solution s-211 (6 ml), spin-coating (layer thickness of about 40 nm) under conditions of 1000 rpm and 30 seconds, and vacuum drying at 60°C for 1 hour to obtain a light emitting layer. Further, using solution s-311 (6 ml), spin-coating under conditions of 1000 rpm and 30 seconds (layer thickness of about 10 nm) and vacuum drying at 60° C. for 1 hour to prepare an electron transport layer that also serves to block holes .

Subsequently, this substrate was fixed to a substrate holder of a vacuum evaporation apparatus, 200 mg of Alq ₃ was put in a resistance heating boat made of molybdenum, and installed in a vacuum evaporation apparatus. After reducing the pressure in the vacuum bath to 4×10 ^-4 Pa, the heating boat containing Alq ₃ was energized and heated, and deposited on the electron transport layer at a deposition rate of 0.1 nm/sec, thereby further forming an electron injection layer having a thickness of 40 nm. Prepared. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Then, 0.5 nm of lithium fluoride and 110 nm of aluminum were deposited to form a cathode, and an organic EL device 1 was fabricated.

In the fabrication of the organic EL device 1, the organic EL device shown in Table 4 in the same manner as in the organic EL device 1, except that the solution s-111, the solution s-211, and the solution s-311 were replaced with the solutions shown in Table 4. Was produced.

<Evaluation of organic EL device>

The following evaluation was performed on the organic EL device shown in Table 4 fabricated as described above, and the results are shown in Table 4.

The fabricated organic EL element is continuously lit by applying a 10V DC voltage in a dry nitrogen gas atmosphere at a temperature of 23°C, and the time when the luminance is reduced by half from the light emission luminance at the start of lighting (hereinafter referred to as light emission lifetime) The efficiency (lm/W) was measured, and the results are shown in Table 4. However, the luminescence lifetime and luminous efficiency are shown by relative values in which the luminescence lifetime and luminous efficiency of the organic EL element 1 are set to 100, respectively. In addition, the luminescence luminance was measured using CS-1000 manufactured by Konica Minolta.

From the results shown in Table 4, when the organic EL device using the coating liquid containing carbon dioxide of the present invention is stored in dry air or air, compared with the coating liquid not containing carbon dioxide under the same conditions, the luminous efficiency and the device It can be seen that the deterioration of the evaluation result of the lifespan is small.

[Example 5]

<Purification of ink compound>

CBP was fractionated under the following conditions using a supercritical fluid chromatography system manufactured by Nippon Bunko Corporation.

Supercritical CO ₂ liquid pump: SCF-Get

Fully automatic pressure regulating valve: SFC-Bpg

Column oven: GC-353B

Injector: 7125i

Column: C18-Silica, 3 μm, 4.6 mm×250 mm

Moving bed: carbon dioxide/toluene=9/1

Moving bed flow rate: 3ml/min

Pressure: 18MPa

Temperature: 40℃

Detection: ultraviolet 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 called Composition 1. Subsequently, except having changed CBP to Ir-14, Ir-1, Ir-15, respectively, it carried out similarly, and the following composition was obtained.

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: Toluene solution containing 10% by mass of Ir-15 and 300 ppm of carbon dioxide

Subsequently, a TFPO solution containing 10 mass% of BCP and 300 ppm of carbon dioxide was obtained in the same manner as the moving layer was changed to carbon dioxide/TFPO = 9/1 and CBP to BCP. This solution is called composition 5.

<Ink adjustment>

(Hole injection layer composition)

PEDOT/PSS mixed aqueous dispersion (1.0% by mass) 20 parts by mass

65 parts by mass of water

10 parts by mass of ethoxyethanol

5 parts by mass of glycerin

PEDOT/PSS: poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (manufactured by Bayer, Baytron P Al 4083)

(Blue light emitting layer composition)

Composition 1 9.5 parts by mass

Composition 2 0.5 parts by mass

40 parts by mass of toluene

50 parts by mass of isobutyl acetate

(Green light emitting layer composition)

Composition 1 9.5 parts by mass

Composition 3 0.5 parts by mass

40 parts by mass of toluene

50 parts by mass of isobutyl acetate

(Red light emitting layer composition)

Composition 1 9.5 parts by mass

Composition 4 0.5 parts by mass

40 parts by mass of toluene

50 parts by mass of isobutyl acetate

(Electron transport layer composition)

Composition 5 10 parts by mass

90 parts by mass of TFPO

<Production of organic EL full color display device>

10 shows a schematic configuration diagram of an organic EL full color display device. After patterning at a pitch of 100 μm on a substrate (NA45 manufactured by NH Techno Glass) on which 100 nm of the ITO transparent electrode 102 was formed as an anode on the glass substrate 101, the ratio between the ITO transparent electrodes on the glass substrate The partition wall 103 (20 µm in width and 2.0 µm in thickness) of photosensitive polyimide was formed by photolithography. Between the polyimide partition walls on the ITO electrode, the hole injection layer composition of the above composition was discharged and injected using an inkjet head (KM512L manufactured by Konica Minolta), and holes having a layer thickness of 40 nm were dried at 200°C for 10 minutes. The injection layer 104 was prepared. On the hole injection layer, the blue light-emitting layer composition, green light-emitting layer composition, and red light-emitting layer composition were similarly injected and injected using an inkjet head to form respective light-emitting layers 105B, 105G, and 105R. Subsequently, the electron transport layer composition was similarly discharged and injected using an inkjet head, and an electron transport layer 106 which also serves as a hole blocking function was formed on each layer of the light emitting layer 105. Finally, on the electron transport layer 106, Al 107 as a cathode was vacuum-deposited to fabricate an organic EL device.

It was found that the fabricated organic EL device emits blue, green, and red light, respectively, by applying a voltage to each electrode, and thus can be used as a full color display device.

[Example 6]

As a p-type material for the bulk heterojunction layer, a low band gap polymer, PCPDTBT described in the literature [Macromolecules 2007, 40, 1981] was synthesized with reference to a non-patent literature (Nature Mat. vol. 6 (2007), p497). Used. In addition, PCBM (purchased from Frontier Carbon) was used as the n-type material.

<Production of organic photoelectric conversion element 1>

On a glass substrate, an indium-tin oxide (ITO) transparent conductive film deposited at 140 nm was patterned to a width of 2 mm using a conventional photolithography technique and hydrochloric acid etching to form a transparent electrode.

The patterned transparent electrode was washed in the order of ultrasonic cleaning with a surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, followed by drying with nitrogen blowing, and finally ultraviolet ozone cleaning. On this transparent substrate, Baytron P4083 (manufactured by Stark V-Tech) as a conductive polymer was spin-coated to a thickness of 60 nm, followed by heating and drying at 140°C for 10 minutes in air.

After this, the substrate was brought into a glove box and worked under a nitrogen atmosphere. First, the substrate was heat-treated at 140° C. for 10 minutes in a nitrogen atmosphere.

Chlorobenzene was prepared by bubbling carbon dioxide gas for 10 minutes, and the dissolved carbon dioxide concentration was measured by gas chromatography, and the concentration was 350 ppm. 1.0% by mass of PCPDTBT as a p-type semiconductor material and 2.0% by mass of [6,6]-phenyl C61-butylate methyl ester (abbreviated as PCBM) (made by Frontier Carbon, NANOM SPECTRA E100H) as an n-type semiconductor material. % And 2.4 mass% of 1,8-octanedithiol was prepared, spin-coating at 1200 rpm for 60 seconds while filtering through a 0.45 µm filter, drying at room temperature for 30 minutes, and photoelectric conversion unit (bulk heterojunction Layer).

Then, the substrate on which the bulk heterojunction layer was formed was installed in a vacuum evaporation apparatus. The device was set so that the 2 mm wide shadow mask was orthogonal to the transparent electrode, and the inside of the vacuum evaporator was reduced to 10 ^-3 Pa or less, and then 0.5 nm of lithium fluoride and 80 nm of Al were deposited. Finally, heating was performed at 120° C. for 30 minutes to obtain an organic photoelectric conversion element 1. In addition, the vapor deposition rate was all deposited at 2 nm/sec, and the size of a square having a side of 2 mm was obtained. The obtained organic photoelectric conversion element 1 was sealed using an aluminum cap and a UV curable resin in a nitrogen atmosphere.

<Evaluation of organic photoelectric conversion elements>

(Evaluation of conversion efficiency)

The fabricated organic photoelectric conversion element was irradiated with light with 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 was superimposed on the light-receiving unit, and the short circuit current density Jsc (mA/cm 2 ). ), the open-circuit voltage Voc (V), and the curve factor (fill factor) FF were respectively measured at four light-receiving portions formed on the same device, and an average value was obtained. Further, the photoelectric conversion efficiency η (%) was calculated from Jsc, Voc, and FF according to Equation 2, and the photoelectric conversion efficiency was 3.9%.

Equation 2 Jsc(mA/㎠)×Voc(V)×FF=η(%)

From the above, it is understood that a highly efficient organic photoelectric conversion element can be manufactured using the coating liquid of the present invention.

The present invention can be used for an ink for electronic device manufacturing, an electronic device, an organic electroluminescent element, and an organic photoelectric conversion element.

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: driving transistor
63: condenser
67: power line
101: glass substrate
102: ITO transparent electrode
103: bulkhead
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 conversion unit (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
B: control unit

Claims (14)

It is a coating liquid containing an organic compound and an organic solvent,
The dissolved carbon dioxide concentration in the organic solvent under conditions of 50°C or less and atmospheric pressure is in the range of 5 to 1000 ppm,
A coating liquid, wherein the organic compound is an organic electroluminescent material. delete The method of claim 1,
When 1 ppm or more of oxygen is present in the coating liquid, the dissolved carbon dioxide concentration is contained within a range of 1.0 to 100000 times the dissolved oxygen concentration under the conditions. The method of claim 1 or 3,
The coating liquid, wherein the coating liquid is a coating liquid for manufacturing an electronic device. The method of claim 4,
The coating liquid, wherein the electronic device is a light emitting device. delete The method of claim 1 or 3,
The coating liquid, characterized in that the coating liquid is an ink jet ink. It is a manufacturing method of a coating liquid for producing the coating liquid according to claim 1 or 3,
A method for producing a coating liquid comprising a step of mixing the organic compound and carbon dioxide. The method of claim 8,
After the step of mixing the organic compound and carbon dioxide, the coating liquid is prepared by using a solution containing the organic compound. The method of claim 8,
A method for producing a coating liquid, comprising the step of separating a substance in a solution containing the organic compound using a supercritical fluid. An ink for electronic device production, comprising the coating liquid according to claim 1 or 3. An electronic device comprising an organic functional layer formed by using the coating liquid according to claim 1 or 3. An organic electroluminescent device comprising an organic functional layer formed using the coating liquid according to claim 1 or 3. A photoelectric conversion element comprising an organic functional layer formed using the coating liquid according to claim 1 or 3.

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