WO2013105445A1 - Electrostatic spraying device - Google Patents

Abstract

In this electrostatic spraying device for depositing an organic thin film using electrostatic spraying, productivity is increased while maintaining uniformity of the formed film and suppressing layer mixing with the base layer. This electrostatic spraying device (1) is configured to be provided with an aerosol generating means which generates an aerosol (12) comprising dispersed charged particles (13) of an organic material, a chamber (10) which stores the aerosol generated by the aerosol generating means, a conveyance path (20) connected at one end to the chamber, a nozzle (30) provided at the other end of the conveyance path, a conveyance means which delivers a carrier gas to convey the aerosol from the chamber via the conveyance path to the nozzle, and a support means which supports a substrate (2) and holds the substrate at a potential difference with the charged particles.

Description

Electrostatic spray equipment

The present invention relates to an electrostatic spray apparatus for forming an organic thin film using an electrostatic spray method.

As a method for producing a plurality of organic thin films such as organic electroluminescence (EL) elements and organic thin film solar cells, there are a vapor deposition method, a wet process (spin coating method, casting method, ink jet method, spray method, printing method) and the like. In recent years, a manufacturing method in a wet process has attracted attention because it does not require a vacuum process and is convenient for continuous production.
However, it is generally known that an organic EL element produced by a wet process does not exhibit sufficient performance in terms of element performance, particularly in terms of life, compared to an organic EL element produced by a vapor deposition method.
When manufacturing a plurality of organic thin films by a wet process, there is a problem that the base layer (lower layer) is dissolved by the solvent at the time of lamination, or layer mixing occurs because the solvent penetrates the base layer. It becomes one of insufficient factors. One way to avoid this problem is to select a solvent that does not dissolve the substrate during lamination, but ensuring the solubility of the organic material in a solvent that does not dissolve the substrate is a major limitation in material design. The condition is the condition.
For this reason, there is a long-awaited method that can reduce the influence of the solvent and can form a large-area film in a non-vacuum. In order to meet such technical demands, attention can be paid to electrostatic spraying.

Patent Documents 1 and 2 describe a technique by an electrostatic spray method.
According to the electrostatic spraying method, the fine particle diameter in the generated aerosol can be reduced to 1 μm or less. Since there is a limit to the amount of spray per nozzle that discharges the fine particles, in order to form a large area with a short tact time, it is conceivable to provide a plurality of nozzles as described in Patent Document 2.

JP 2011-03442 A JP 2011-181271 A

However, in the case where a plurality of nozzles are provided, the amount of deposition varies between a region where the fine particles are given by one nozzle, a region where the fine particles are given by another adjacent nozzle, and a region where both overlap, The problem of uneven thickness and film quality arises.
Further, when the supply amount of the solution serving as the aerosol raw material is increased, there are problems that the atomization is not in time and the liquid drips or the particle diameter in the aerosol is not sufficiently reduced.
Furthermore, if the nozzle is brought closer to the base material in order to speed up the takt time, the solute will not be sufficiently atomized and the solvent will not be sufficiently volatilized, resulting in layer mixing and a factor in performance degradation. .

The present invention has been made in view of the above problems in the prior art, and in an electrostatic spraying apparatus for forming an organic thin film using an electrostatic spraying method, the uniformity of the film to be formed and the underlying layer It is an object to improve productivity while suppressing the mixing of layers.

The invention according to claim 1 for solving the above-mentioned problems is an electrostatic spray apparatus for forming an organic thin film on a substrate using an electrostatic spray method.
Aerosol generating means for generating an aerosol in which charged fine particles including an organic material are dispersed;
A chamber for storing the aerosol generated by the aerosol generating means;
A transfer path having one end connected to the chamber;
A nozzle provided at the other end of the transport path;
Transport means for transporting the aerosol from the chamber to the nozzle through the transport path;
Supporting means for supporting the base material and holding the base material with a potential difference from the potential of the fine particles,
The electrostatic spraying apparatus is characterized in that fine particles in aerosol sprayed by the nozzle are attracted to the substrate by electrostatic attraction to form the organic thin film.

The invention according to claim 2 is the electrostatic spray device according to claim 1, wherein a plurality of the aerosol generating means are provided in the chamber.

The invention according to claim 3 has a plurality of sets of the aerosol generating means, the chamber, and the one end, and the transport path includes a joining portion that joins between the one end and the other end of each set. The electrostatic spray device according to claim 1, wherein the electrostatic spray device is provided.

According to a fourth aspect of the present invention, there is provided voltage applying means for applying a voltage to the transport path to charge the surface of the transport path for transporting the fine particles to the same charge as the fine particles. It is an electrostatic spray apparatus as described in any one of claim | item 3.

The invention of claim 5 is the electrostatic spray device according to any one of claims 1 to 4, wherein the substrate is held on a stage to which a voltage is applied.

6. The electrostatic spray device according to claim 1, further comprising moving means for relatively moving at least one of the base material or the nozzle. It is.

The invention of claim 7 is the electrostatic spray device according to any one of claims 1 to 6, wherein the base material is a belt-like base material.

The invention according to claim 8 is the electrostatic spray device according to any one of claims 1 to 7, wherein the organic thin film is an organic thin film of an organic electroluminescence element.

The invention of claim 9 is the electrostatic spray apparatus according to claim 8, wherein the organic thin film of the organic electroluminescence element is a light emitting layer.

According to the present invention, the charged and atomized organic material is stored in the chamber upstream of the nozzle sprayed on the base material, and is transported to the nozzle, so that it is supplied to the nozzle in a large amount without dripping. It is possible to bring the nozzle and the substrate closer because there is no need to obtain solute atomization and solvent volatilization in the space between the nozzle and the substrate. Productivity can be improved by increasing the deposition area and deposition rate.
In particular, by providing a plurality of sets of aerosol generating means and chambers, a large amount of aerosol can be generated and supplied. In this case, the aerosol is merged from a plurality of chambers and conveyed to a common nozzle for spraying. Therefore, the problem of non-uniform film thickness and film quality that occurs when a plurality of nozzles are provided does not occur.
As described above, according to the present invention, there is an effect that productivity can be improved while maintaining uniformity of a film to be formed and suppressing layer mixing with the base layer.

1 is a schematic configuration diagram illustrating an electrostatic spray device according to an embodiment of the present invention. It is a perspective view of the part containing the nozzle of the electrostatic spray apparatus which concerns on one Embodiment of this invention. It is a structure schematic diagram which shows the modification of the electrostatic spray apparatus which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

First, an embodiment of the present invention will be described with reference to FIGS.
The electrostatic spray apparatus 1 according to the present embodiment is an apparatus that forms an organic thin film, which serves as a light emitting layer of an organic electroluminescence element, on a substrate 2 by using an electrostatic spray method with a configuration described below.
The electrostatic spray device 1 includes a chamber 10 equipped with an aerosol generating device, a transport path 20, a nozzle 30, a transport device 40, and a substrate support moving device 50.

In the chamber 10, a solution 11 in which an organic material is dissolved, an aerosol 12 generated using the solution 11 as a raw material, and charged fine particles 13 contained in the aerosol 12 are schematically shown. The fine particles 13 are made of an organic material and a solvent dissolved as a solute in the solution 11. The charged fine particles 13 are charged and atomized and dispersed in the aerosol 12.

The aerosol generating apparatus for generating such an aerosol 12 is not particularly limited, and a technique that can be used may be selected and implemented. For example, an apparatus using an ultrasonic atomization phenomenon is known and can be applied. In that case, the solution 11 is ultrasonically vibrated by an ultrasonic vibrator attached to the bottom of the chamber 10 to generate the aerosol 12 from the liquid surface of the solution 11. At this time, an electrostatic atomizer that applies a high voltage to the liquid surface of the solution 11 or an ultrasonic atomizer ionizer that supplies ion carrier gas from the side onto the liquid surface of the solution 11 can be applied. In the latter case, since the aerosol 12 can be transported in the direction of the nozzle 30 by the ion carrier gas, the device for supplying the ion carrier gas can be the transport device 40.
Moreover, what sprays the solution 11 with a nozzle is also applicable so that it may be used conventionally by the existing electrostatic spray apparatus. In this case, the aerosol 12 is stored in the chamber 10 by disposing the nozzle outlet in the chamber 10. A plurality of nozzles may be provided for one chamber 10. In the case of using a nozzle for generating aerosol, regardless of the configuration shown in FIG. 1, the storage portion for the solution 11 does not have to be in the chamber 10, and an aerosol generating device may be provided outside the chamber 10. In addition, when a nozzle is used for generating aerosol, a well-known method is selected and applied regardless of any method of applying a voltage for charging to the nozzle, a method of applying to the solution 11, or a method of applying to the aerosol 12. can do.

The transfer device 40 includes a gas tank 41 filled with a carrier gas, a compressor 42, a valve 43, and the like, and sends the carrier gas 44 to an internal space in which the aerosol 12 in the chamber 10 is stored.
As the carrier gas 44, a gas such as nitrogen, argon, helium, or air can be used.
The conveyance path 20 is configured by piping. One end of the conveyance path 20 is connected to the chamber 10, and the aerosol 12 is conveyed from the chamber 10 to the nozzle 30 via the conveyance path 20 by the carrier gas 44 delivered from the conveyance device 40.

As shown in FIG. 1, a plurality of device configurations A including a chamber 10 equipped with an aerosol generation device, a transfer device 40, and one end 21 of a transfer path 20 connected to the chamber 10 are provided.
The conveyance path 20 has a joining portion 22 that joins one end portions 21, 21... Connected to the chambers 10, 10..., And reaches the other end portion 23 through the joining portion 22. The other end 23 is provided with a nozzle 30. Therefore, the aerosols 12 supplied from the respective chambers 10, 10... Merge and are all supplied to the nozzle 30 and sprayed from the nozzle 30.

As shown in FIG. 1 and FIG. 2, the nozzle 30 reduces the flow path cross-sectional area toward the discharge port 33 continuously with the storage section 31 having a uniform flow path cross section that temporarily stores the aerosol 12 and the storage section 31. The reduction part 32 and the brim-shaped suppression member 34 by which the bottom face is arrange | positioned on the same plane as the discharge outlet 33 are provided. The brim-like suppressing member 34 may be omitted, but it is possible to suppress the aerosol from being scattered and scattered by the entrained air generated when the base material 2 is transported, and it is better to be provided because the adhesion efficiency increases. preferable.
The discharge port 33 is formed in a long rectangular shape, and is disposed so as to extend in the width direction orthogonal to the scanning direction of the base material 2, and has a large width for film formation.
The storage unit 31 is provided so that the aerosol 12 is discharged uniformly regardless of the position in the discharge port 33. The other end 23 of the transport path 20 is connected to both sides of the storage section 31, and the aerosol 12 transported through the transport path 20 flows into the storage section 31 from both sides orthogonal to the discharge port 33 direction. The entire space in the nozzle 30 is uniformly filled and discharged from the discharge port 33. Thereby, the aerosol 12 is uniformly discharged regardless of the position in the discharge port 33.

The substrate support moving device 50 includes a stage 51 that supports the substrate 2. Further, the substrate support moving device 50 has means for holding the substrate 2 with a potential difference from the potential of the charged fine particles 13 in order to apply an electrostatic attractive force to the charged fine particles 13 to the substrate 2. As a means for this, as shown by the voltage application means 52 in FIG. The structure which applies can be applied. The voltage applying unit 24 and the voltage applying unit 52 are illustrated as an example in which the charged fine particles 13 are positively charged.
Further, the substrate support moving device 50 has a moving mechanism for the stage 51. One moving axis of the moving mechanism is a direction orthogonal to the discharge direction of the nozzle 30 and the longitudinal direction of the discharge port 33, and scans the substrate 2 placed on the stage 51. Since this scanning can be realized by relative movement between the nozzle 30 and the substrate 2, it can of course be implemented as a configuration in which the nozzle 30 is moved.
The charged fine particles 13 reaching the discharge port 33 of the nozzle 30 fly toward the base material 2 by an electrostatic attractive force due to a potential difference with the base material 2 in addition to the gas pressure by the aerosol 12 and the carrier gas 44, and the like. A film is formed by adhering to and depositing on the surface of the substrate 2.
In addition, a mechanism for collecting the aerosol 12 that has not adhered to the substrate 2 may be provided around the nozzle discharge port 33.
As described above, the electrostatic spray apparatus 1 forms an organic thin film.
Even if the charged fine particles 13 discharged from the discharge port 33 are drawn and flowed in the moving direction of the base material 2 by the movement of the base material 2 with respect to the discharge port 33 in the film forming process, the charged fine particles are caused by the suppressing member 34. 13 is suppressed, and the charged fine particles 13 can be efficiently guided to adhere to the substrate 2.

The chamber 10, the conveyance path 20, and the nozzle 30 are preferably charged to the same charge as the charged fine particles 13 so that the charged fine particles 13 do not adhere. The charged fine particles 13 are prevented from adhering due to electrostatic repulsion, and the charged fine particles 13 can be conveyed to the discharge port 33 with high yield.
For this purpose, it is effective to use a non-conductive material as a constituent material of the chamber 10, the conveyance path 20, and the nozzle 30. In this case, initially, the charged fine particles 13 adhere to the surfaces of the chamber 10, the conveyance path 20, and the nozzle 30. However, the charged fine particles 13 instantly charge the same surface to the same pole as the charged fine particles 13, and thereafter the charged fine particles 13 do not adhere due to electrostatic repulsion. The non-conductive material is preferably a synthetic resin, an elastomer or the like from the viewpoint of facilitating charging. For example, acrylic, vinyl chloride, polyethylene, polystyrene, polyurethane, polyester, rubber, Teflon (registered trademark), Cellophane, celluloid, etc. are mentioned.
It is also effective to configure the chamber 10, the conveyance path 20 and the nozzle 30 with a metal substrate covered with a dielectric. In this case, the dielectric can be charged by applying a voltage to the metal substrate with the voltage applying means 24 as shown in FIG. 1, and the charge amount can be controlled by changing the voltage value. The charged fine particles 13 can be classified by controlling the charge amount. For example, when the charging of the transport path 20 is small, the repulsive force acting on the charged fine particles 13 is small. Therefore, the charged fine particles 13 having a small diameter do not contact the conveyance path, but the charged fine particles 13 having a large diameter are in contact with each other, and the charged fine particles 13 having a large diameter are not conveyed to the substrate 2 and a more uniform thin film is obtained. When it is desired to use the large charged fine particles 13 for film formation, the charge amount may be increased, and the charge amount of the convenient conveyance path 20 may be selected depending on the desired film quality. Examples of the dielectric include those obtained by spraying Al2O3 ceramics and then sealing with alkoxysilane. A metal such as silver, platinum, stainless steel, aluminum, or iron can be used for the metal substrate. Stainless steel is easy to process and can be preferably used. As the dielectric, silicate glass, borate glass, phosphate glass, germanate glass, tellurite glass, aluminate glass, vanadate glass, etc. can be used. . Of these, borate glass is easy to process.
It is also preferable to use a ceramic obtained by sintering a highly heat-resistant ceramic with high airtightness. The thickness of the ceramic may be in a range that can withstand the applied voltage, and is preferably 0.1 mm or more, and more preferably 0.3 mm or more. Examples of the ceramic material include alumina-based, zirconia-based, silicon nitride-based, and silicon carbide-based ceramics. Among these, alumina-based ceramics are preferable, and among the alumina-based ceramics, Al 2 O 3 is particularly preferable.
The ceramic is preferably sealed with an inorganic material, whereby the durability of the metal substrate can be improved. The sealing process is a metal having a uniform structure by forming a solid three-dimensional bond by applying a sol whose main raw material is a metal alkoxide, which is a sealing agent, to ceramics and then gelling and curing. Ceramics can be sealed with an oxide. Moreover, it is preferable to perform energy treatment in order to promote the sol-gel reaction. By applying energy treatment to the sol, a three-dimensional bond of metal-oxygen-metal can be promoted. For the energy treatment, plasma treatment, heat treatment at 200 ° C. or lower, and UV treatment are preferable.

Further, a heater may be attached to the constituent materials of the chamber 10, the conveyance path 20 and the nozzle 30. For example, a heater is attached so as to cover the outside of the constituent materials of the chamber 10, the conveyance path 20, and the nozzle 30. With this heater, the temperature of the aerosol 12 to be conveyed can be maintained at an optimum value for vaporizing the solvent, and the removal of the solvent can be promoted during the conveyance, and the diameter of the charged fine particles 13 can be further reduced. . Further, when the charged fine particles 13 adhere to the substrate 2, the solvent is instantaneously removed, and layer mixing can be suppressed. The temperature is set according to the volatility of the solvent used. Further, a plurality of aerosol generation devices and chambers 10 may be used, and the aerosol 12 generated in each chamber 10 may be merged in the conveyance path 20, or a merge chamber is prepared and merged and then conveyed to the nozzle 30. Also good. Use multiple aerosol generators and chambers to control the film quality by supplying raw material liquids with different solutes / solute ratios / concentrations to each aerosol generator, or by changing the spray amount of each nozzle over time. can do. For example, in the light emitting layer in organic electroluminescence, the ratio of the dopant and the host can be easily adjusted. Furthermore, a coating solution in which the material of each layer is dissolved is prepared, and the solute concentration or aerosol generation amount is adjusted according to the ratio to be mixed with the layer, and the layers are mixed and applied in the conveyance path, thereby reducing the layer mixing amount. It can also be adjusted.
The particle size of the fine particles is not particularly limited, but the particle size of the aerosol generated in the chamber is generally preferably about 0.1 to 100 μm, preferably about 0.1 to 10 μm. Is more preferable, and further 0.1 to 1 μm is preferable.
The fine particle diameter of the aerosol ejected from the nozzle discharge port 33 to the substrate 2 is more preferably about 0.1 to 10 μm, and preferably 0.01 to 1 μm.

Further, from the viewpoint of increasing the yield in the film forming process, the base material 2 should be kept at a temperature lower than the gas temperature discharged from the nozzle 30 in order to suppress the upward air flow from the base material 2 toward the nozzle 30. preferable. For example, when the chamber 10, the conveyance path 20, and the nozzle 30 are heated as described above, the temperature is adjusted by a temperature adjustment device attached to the stage 51 to a temperature lower than that temperature.
Moreover, there is no restriction | limiting in particular about the distance of the aerosol discharge port of the nozzle 30, and a base material, but the one where a distance is near is preferable from a viewpoint of raising a yield. A preferable distance is 0.1 to 10 mm, and more preferably 0.5 to 5 mm. Since the transport path 20 is provided, the solvent of the aerosol can be removed through the transport path, so that layer mixing does not occur even when the aerosol discharge port of the nozzle 30 is brought close to the substrate.
Further, when forming a film in a wider range, the nozzles 30 may be arranged in a direction perpendicular to the conveyance direction of the substrate 2. Further, in order to improve productivity, the nozzles 30 may be arranged in the transport direction of the base material 2. By separating the aerosol generating part (A) and the aerosol discharge part (nozzle 30) and connecting them by the conveyance path 20, and by forming the slit-like nozzle discharge port 33, the aerosol discharge part can be reduced in size. It can be easily arranged in the width and the longitudinal direction of the material 2.

As the substrate support moving device 50, a roller transport device 50A can be applied as in the electrostatic spray device 1A shown in FIG.
The roller conveyance device 50A has a known configuration in which a belt-like base material 2 (band-like base material) is wound and held on rollers 53, 53... Including at least one drive roller. At least one roller 53 is composed of a cylindrical metal base material and a dielectric covering its outer peripheral surface, a voltage is applied to the metal base material, and the base material 2 is brought into contact with the base material 2 2 is charged. As the metal substrate and the dielectric applied to the charging roller 53, the same materials as the constituent materials of the chamber 10, the conveyance path 20, and the nozzle 30 described above can be applied.
Moreover, since the organic solvent adhering to a base material can be reduced, the load of the drying process after application | coating can be reduced. Furthermore, since the lower layer can be applied without dissolving it, the same layer can be applied sequentially with the same solvent and material. By applying sequentially until the desired film thickness is obtained, it is easier to remove the solvent in the film and improve quality. Is also planned. When the same layer is applied successively, the film thickness after drying in one application is preferably 1 to 30 nm, more preferably 10 to 20 nm.

The aerosol 12 is generated in the plurality of chambers 10, 10,... By the electrostatic spray device according to the embodiment described above, and further, the charged fine particles 13 are atomized and the solvent is volatilized. The charged fine particles 13 are conveyed through the conveying path 20 while preventing the charged fine particles 13 from adhering to the nozzles 30, and a large amount of charged fine particles 13 made of an organic material are applied to the base material 2 from the nozzles 30. However, a large-area organic thin film can be formed with high efficiency, and the productivity of the organic electroluminescence element can be improved. In addition, it is applicable to manufacture of a device having an organic thin film such as an organic thin film solar cell.

〔solvent〕
Next, the solvent used for producing the fine particles according to the present invention will be described in detail.
Examples of the liquid medium for dissolving or dispersing the organic material according to the present invention include halogen-based hydrocarbon solvents such as dichloromethane, dichloroethane, chloroform, tetrachloroethane, trichloroethane, and chlorobenzene, and ether-based solvents such as dibutyl ether and tetrahydrofuran. , Methanol, alcohol solvents such as ethanol, isopropanol, cyclohexanol, aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, paraffin solvents such as hexane, octane, decane, ethyl acetate, butyl acetate, acetic acid Ester solvents such as amyl, amide solvents such as N, N-dimethylformamide, N-methylpyrrolidone, ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, acetonitrile, DMF Solvent DMSO, and the like.
Furthermore, in order to control the particle size, it is preferable to use a solution obtained by mixing two or more solvents having different vapor pressures from the above solvents. Furthermore, in order to control the wettability of the fine particles when the fine particles adhere to the substrate and to improve the uniformity and smoothness of the film thickness, a solution in which two or more solvents having different surface tensions are mixed is used as the solvent. It is preferable to use it.
[Organic materials]
Next, the organic material used for producing the fine particles according to the present invention will be described in detail.
The organic material for forming the organic thin film according to the present invention is largely a polymer or a low molecule.
A low molecule means a weight average molecular weight of 5000 or less, and preferably used as a low molecule is 3000 or less, more preferably 2000 or less. A polymer refers to a polymer larger than 5000.
When applying a low molecular weight material, unlike a high molecular weight material, even if a solvent that does not dissolve the lower layer is used, the low molecular weight, that is, the molecule is small, so the solvent penetrates into the lower layer and the low molecular weight material also penetrates. , Layer mixing is likely to occur, causing performance degradation.

[Organic EL element (Organic electroluminescence element)
Next, the organic electroluminescence element will be described.
An organic electroluminescence element has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer to recombine excitons. It is an element that emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated. Preferred specific examples of the layer structure of the organic EL element are shown below.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode Here, the light emitting layer preferably contains at least two kinds of light emitting materials having different emission colors, and a single layer or a light emitting layer comprising a plurality of light emitting layers A unit may be formed. The hole transport layer also includes a hole injection layer and an electron blocking layer.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

The structure of the light emitting layer according to the present invention is not particularly limited as long as the light emitting material included satisfies the above requirements.

Also, there may be a plurality of layers having the same emission spectrum or emission maximum wavelength.

It is preferable to have a non-light emitting intermediate layer between each light emitting layer.

In the present invention, the total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably 30 nm or less because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in the field of this invention is a film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.

The film thickness of each light emitting layer is preferably adjusted in the range of 1 to 50 nm, more preferably in the range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.

For the production of the light emitting layer, a light emitting material or a host compound, which will be described later, is formed by forming a film by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, an ink jet method, or the like. it can.

In the present invention, a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.

In the present invention, the light emitting layer preferably contains a host compound and a light emitting material (also referred to as a light emitting dopant compound) and emits light from the light emitting material.

As the host compound contained in the light emitting layer of the organic EL device according to the present invention, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.

As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of luminescent material mentioned later, and can thereby obtain arbitrary luminescent colors.

The host compound used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). )But it is good.

As the known host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents an increase in emission wavelength, and has a high Tg (glass transition temperature) is preferable. Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579 No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. No. 2002-302516, No. 2002-305083, No. 2002-305084, No. 2002-308837, and the like.

Next, the light emitting material will be described.

As the light-emitting material according to the present invention, a fluorescent compound or a phosphorescent material (also referred to as a phosphorescent compound or a phosphorescent compound) is used.

In the present invention, a phosphorescent material is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is 0 at 25 ° C. A preferred phosphorescence quantum yield is 0.1 or more, although it is defined as 0.01 or more compounds.

The phosphorescent quantum yield can be measured by the method described in Spectra II, page 398 (1992 version, Maruzen) of Experimental Chemistry Lecture 4 of the 4th edition. The phosphorescence quantum yield in a solution can be measured using various solvents. However, when a phosphorescent material is used in the present invention, the phosphorescence quantum yield (0.01 or more) is achieved in any solvent. Just do it.

There are two types of light emission of the phosphorescent material. In principle, the carrier recombination occurs on the host compound to which the carrier is transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent material. Energy transfer type to obtain light emission from the phosphorescent light emitting material, and another one is that the phosphorescent light emitting material becomes a carrier trap, and recombination of carriers occurs on the phosphorescent light emitting material, and light emission from the phosphorescent light emitting material is obtained. Although it is a trap type, in any case, the excited state energy of the phosphorescent material is required to be lower than the excited state energy of the host compound.

The phosphorescent light-emitting material can be appropriately selected from known materials used for the light-emitting layer of the organic EL element, and is preferably a complex compound containing a group 8-10 metal in the periodic table of elements. More preferably, an iridium compound, an osmium compound, a platinum compound (platinum complex compound), or a rare earth complex, and most preferably an iridium compound.

Fluorescent light emitters can also be used for the organic electroluminescence device according to the present invention. Representative examples of fluorescent emitters (fluorescent dopants) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes. Examples thereof include dyes, perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

Conventionally known dopants can also be used in the present invention. For example, International Publication No. 00/70655 pamphlet, JP-A Nos. 2002-280178, 2001-181616, 2002-280179, 2001 -181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671, 2001-345183, 2002 No. 324679, WO 02/15645, JP 2002-332291, 2002-50484, 2002-332292, 2002-83684, JP 2002-540572, JP 002-117978, 2002-338588, 2002-170684, 2002-352960, WO01 / 93642, JP2002-50483, 2002-1000047 No. 2002-173684, No. 2002-359082, No. 2002-175484, No. 2002-363552, No. 2002-184582, No. 2003-7469, No. 2002-525808 JP2003-7471, JP2002-525833A, JP2003-31366A, 2002-226495, 2002-234894, 2002-233506, 2002-2417. No. 1, No. 2001-319779, No. 2001-319780, No. 2002-62824, No. 2002-1000047, No. 2002-203679, No. 2002-343572, No. 2002-203678. Gazettes and the like.

In the present invention, at least one light emitting layer may contain two or more kinds of light emitting materials, and the concentration ratio of the light emitting materials in the light emitting layer may vary in the thickness direction of the light emitting layer.

《Middle layer》
In the present invention, a case where a non-light emitting intermediate layer (also referred to as an undoped region) is provided between the light emitting layers will be described.

In the case of having a plurality of light emitting layers, the non-light emitting intermediate layer is a layer provided between the light emitting layers.

The film thickness of the non-light emitting intermediate layer is preferably in the range of 1 to 20 nm, and more preferably in the range of 3 to 10 nm to suppress interaction such as energy transfer between adjacent light emitting layers, and This is preferable because a large load is not applied to the voltage characteristics.

The material used for the non-light emitting intermediate layer may be the same as or different from the host compound of the light emitting layer, but may be the same as the host material of at least one of the adjacent light emitting layers. preferable.

The non-light-emitting intermediate layer may contain a non-light-emitting layer, a compound common to each light-emitting layer (for example, a host compound), and each common host material (where a common host material is used) Including the case where the physicochemical characteristics such as phosphorescence emission energy and glass transition point are the same, and the case where the molecular structure of the host compound is the same, etc.) The barrier is reduced, and the effect of easily maintaining the injection balance of holes and electrons even when the voltage (current) is changed can be obtained. Furthermore, by using a host material having the same physical characteristics or the same molecular structure as the host compound contained in each light-emitting layer in the undoped light-emitting layer, device fabrication, which is a major problem in conventional organic EL device fabrication, is achieved. Complexity can also be eliminated.

In the case of using the organic EL element in the present invention, the host material is responsible for carrier transportation, and therefore a material having carrier transportation ability is preferable. Carrier mobility is used as a physical property representing carrier transport ability, but the carrier mobility of an organic material generally depends on the electric field strength. Since a material having a high electric field strength dependency easily breaks the balance between injection and transport of holes and electrons, it is preferable to use a material having a low electric field strength dependency of mobility for the intermediate layer material and the host material.

On the other hand, in order to optimally adjust the injection balance of holes and electrons, it is also preferable that the non-light emitting intermediate layer functions as a blocking layer described later, that is, a hole blocking layer and an electron blocking layer. It is done.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

The details of the anode buffer layer (hole injection layer) are also described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented 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 (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and the forefront of industrialization (published by NTT Corporation on November 30, 1998)” on page 237. There is a hole blocking (hole blocking) layer.

In a broad sense, the hole blocking layer has a function of an electron transport layer and is composed of a hole blocking material having a function of transporting electrons and having a remarkably small ability to transport holes, while transporting electrons. By blocking holes, the recombination probability of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed. The hole blocking layer is preferably provided adjacent to the light emitting layer.

On the other hand, the electron blocking layer, in a broad sense, has a function of a hole transport layer, and is made of a material having a function of transporting holes while having a remarkably small ability to transport electrons, while transporting holes. By blocking electrons, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transporting layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has either hole injection or transport or electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds 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-tolyl) Aminophenyl) -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) quadriphenyl 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-diphenylaminostilbenzene; N-phenylcarbazole, and also two described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

Also, JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, it is preferable to use these materials because a light-emitting element with higher efficiency can be obtained.

The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. The thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use a hole transport layer having a high p property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the 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 an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq3), 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) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. Further, the distyrylpyrazine derivatives exemplified as the material for the light emitting layer can also be used as the electron transport material, and inorganic semiconductors such as n-type-Si and n-type-SiC can be used as well as the hole injection layer and the hole transport layer. It can be used as an electron transport material.

The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. The thickness of the electron transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use an electron transport layer having a high n property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be produced.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such an electrode material include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, and ZnO. Alternatively, an amorphous material such as In2O3-ZnO that can form a transparent conductive film may be used.

For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not required (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material.

Alternatively, when a material that can be applied such as an organic conductive compound is used, a wet film forming method such as a printing method or a coating method can be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

"cathode"
As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2O3) mixture. , Indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. In order to transmit the emitted light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

In addition, a transparent or semi-transparent cathode can be produced by producing the conductive transparent material mentioned in the description of the anode on the cathode after producing the metal with a film thickness of 1 nm to 20 nm. By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.
The compounds used in the examples are shown below.

<< Production of organic EL element >>
[Production of Organic EL Element 1]
After patterning a substrate (NH technoglass NA45) formed by depositing 100 nm of ITO (indium tin oxide) on a 100 mm × 100 mm × 1.1 mm glass substrate as an anode, a substrate provided with this ITO transparent electrode was formed. Ultrasonic cleaning with isopropyl alcohol, drying with dry nitrogen gas, and UV ozone cleaning were performed for 5 minutes. A solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) to 70% with pure water on this substrate was spin-coated at 3000 rpm for 30 seconds. After film formation by the method, the substrate surface temperature was set to 200 ° C. and dried for 1 hour to provide a hole injection layer having a thickness of 30 nm.
This substrate was transferred to a glove box under a nitrogen atmosphere according to JIS B 9920, with a measured cleanliness of class 100, a dew point temperature of −80 ° C. or lower, and an oxygen concentration of 0.8 ppm. A coating solution for a hole transport layer was prepared as follows in a glove box, and applied with a spin coater under conditions of 1500 rpm and 30 seconds. This substrate was dried by heating at a substrate surface temperature of 150 ° C. for 30 minutes to provide a hole transport layer. The film thickness was 20 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Coating liquid for hole transport layer)
Monochlorobenzene 100g
Poly- (N, N′-bis (4-butylphenyl) -N, N′-bis (phenyl) benzidine) (ADS254BE: manufactured by American Die Source) 0.5 g

Next, the substrate provided up to the hole transport layer was moved to the electrostatic spray device without being exposed to the atmosphere, and the light emitting layer coating solution prepared as described below in a nitrogen atmosphere was the electrostatic spray device 1 shown in FIG. Was applied under the conditions described in Table 1. The substrate surface temperature was set to 120 ° C. and dried to provide a light emitting layer. When the coating was performed under the same conditions on a separately prepared substrate and measured, the film thickness was 40 nm. Further, the coating was performed under the same conditions on another substrate, and the time required for the residual solvent ratio to become 5 wt% or less was 10 minutes (substrate surface temperature 120 ° C.). Moreover, when the liquid feeding amount was calculated from the change amount of the liquid amount before and after coating, it was 10 ml / min.
(Light emitting layer coating solution)
Butyl acetate 100g
HA 0.1g
DA 0.011g
DB 0.002g
DC 0.002g
Before film formation, aerosol generation and transfer were performed until the vapor pressure of butyl acetate in the chamber, transfer path, and nozzle was stabilized, and then the substrate was moved to form a film.

Next, using the electrostatic spray device 1 shown in FIG. 1 for the electron transport layer coating solution prepared as described below under a nitrogen atmosphere without being exposed to the atmosphere, the conditions other than the solvents described in Table 1 were the same. And applied. Further, the substrate was heated and dried at 120 ° C. for 30 minutes to provide an electron transport layer. The film thickness was 30 nm when it applied and measured on the conditions prepared with the board | substrate prepared separately.
(Coating liquid for electron transport layer)
2,2,3,3-tetrafluoro-1-propanol 100g
ET-A 0.75g

Next, the substrate provided up to the electron transport layer was moved to a vapor deposition machine without being exposed to the atmosphere, and the pressure was reduced to 4 × 10 −4 Pa. Note that potassium fluoride and aluminum were each placed in a tantalum resistance heating boat and attached to a vapor deposition machine.
First, a resistance heating boat containing potassium fluoride was energized and heated to provide 3 nm of an electron injection layer made of potassium fluoride on the substrate. Subsequently, a resistance heating boat containing aluminum was energized and heated, and a cathode having a thickness of 100 nm made of aluminum was provided at a deposition rate of 1 to 2 nm / second.
The substrate provided up to the cathode is moved to a glove box with a cleanliness measured in accordance with JIS B9920, class 100, dew point temperature of -80 ° C or less, and oxygen concentration of 0.8 ppm without being exposed to air. The organic EL element 101 was obtained by sealing with a glass sealing can attached with barium oxide as a water-absorbing agent. Barium oxide, a water-absorbing agent, is a high-purity barium oxide powder manufactured by Aldrich, and is attached to a glass sealing can with a fluorine-based semipermeable membrane (Microtex S-NTF8031Q made by Nitto Denko) with an adhesive. Were prepared and used in advance. An ultraviolet curable adhesive was used for adhesion between the sealing can and the organic EL element, and the organic EL element 1 was produced by adhering the two by irradiation with ultraviolet rays.

[Production of Organic EL Element 2]
The light emitting layer coating solution was changed to the coating solution described below, and an organic EL device 2 was produced in the same manner as the organic EL device 1 under the conditions shown in Table 1. When the coating was performed under the same conditions on a separately prepared substrate and measured, the film thickness was 40 nm. In addition, the time required for coating with another substrate under the same conditions and for the residual solvent ratio to be 5 wt% or less was 10 minutes. Moreover, when the liquid feeding amount was calculated from the change amount of the liquid amount before and after coating, it was 10 ml / min.
(Light emitting layer coating solution)
Toluene 100g
HA 1g
DA 0.11g
DB 0.002g
DC 0.002g

[Production of organic EL elements 3 to 6]
The coating solution for the light emitting layer of the organic EL element 1 was produced in the same manner as the organic EL element 1 except for the conditions described in Table 1. When the coating was performed under the same conditions on a separately prepared substrate and measured, the film thickness was 40 nm. In addition, the time required for coating with another substrate under the same conditions and the residual solvent ratio to be 5 wt% or less was as shown in Table 2 (“drying time (min)”).

[Production of Organic EL Element 7]
An organic EL device 7 was prepared in the same manner as the organic EL device 1 except that the light emitting layer coating solution prepared as described below was prepared under the conditions shown in Table 1. When the coating was performed under the same conditions on a separately prepared substrate and measured, the film thickness was 40 nm. In addition, the time required for coating with another substrate under the same conditions and the residual solvent ratio to be 5 wt% or less was as shown in Table 2 (“drying time (min)”).
(Light emitting layer coating solution)
Toluene 80g
Butyl acetate 20g
HA 0.8g
DA 0.088g
DB 0.0016g
DC 0.0016g

[Production of Organic EL Element 8]
In the same manner as in the organic EL element 1, a base material formed up to the hole transport layer was prepared.
Subsequently, the light emitting layer coating liquid prepared as follows was applied in the following order under the conditions described in Table 1 using the electrostatic spray device 1 shown in FIG.
As the first pass, the light emitting layer coating solution described below was applied at a conveyance speed of 1.8 m / min. Thereafter, the substrate was dried at a substrate surface temperature of 120 ° C. The film thickness was 20 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately. Subsequently, the light emitting layer coating liquid was applied at a conveyance speed of 1.8 m / min as the second pass. Thereafter, the substrate was dried at a substrate surface temperature of 120 ° C. The film thickness was 40 nm when it applied and measured on the board | substrate with which the issue layer 20nm application | coating was carried out on the same conditions on the board | substrate prepared separately.
The total time of the two drying times required until the residual solvent ratio is 5 wt% or less is as shown in Table 2 (“Drying time (min)”). Met.
(Light emitting layer coating solution)
Butyl acetate 100g
HA 0.05g
DA 0.0055g
DB 0.0001g
DC 0.001g
Next, sealing with an electron transport layer, an electron injection layer, a cathode and glass was performed in the same manner as in Example 1 to produce a sealing element.

[Production of Organic EL Element 9]
The following two types of coating solutions for the light emitting layer were prepared, and the two types of coating solutions were put in different chambers, and a light emitting layer was formed under the conditions shown in Table 1.
(Light-Emitting Layer Coating Solution 1)
Butyl acetate 100g
HA 0.1g
DB 0.002g
DC 0.002g
(Light emitting layer coating solution 2)
Toluene 100g
DA 0.11g
In addition, the liquid feeding amount was 10 ml / min for the light emitting layer coating solution 1 and 1 ml / min for the light emitting layer coating solution 2.

[Production of Organic EL Element 10] (Comparative Example)
The light emitting layer coating solution prepared as described below was applied using an electrostatic spray apparatus 1 so that a 100 mm square substrate had a thickness of 40 nm under the conditions shown in Table 1. Thereafter, the substrate was dried at a substrate surface temperature of 120 ° C. to provide a light emitting layer. The amount of liquid fed per nozzle at this time was 60 μl / min. When coating was performed under the same conditions on a separately prepared substrate and measured, the film was formed 6 times while shifting the position, and the film thickness was 100 mm □ and the film thickness was 40 nm. The temperature of the atmosphere at this time was 25 ° C.
(Light emitting layer coating solution)
Butyl acetate 100g
HA 0.1g
DA 0.011g
DB 0.002g
DC 0.002g
After that, similarly to the organic EL element 1, the electron transport layer and the subsequent layers were applied to prepare the organic EL element 10.

[Production of Organic EL Element 11] (Comparative Example)
When the light emitting layer was applied, an organic EL element 11 was produced in the same manner as the organic EL element 1 except for the conditions listed in Table 1.

[Preparation of Organic EL Element 12] (Comparative Example)
An organic EL element 12 was produced in the same manner as the organic EL element 1 except that the light emitting layer was applied as follows.
A coating solution for the light-emitting layer was prepared as follows, and was applied with the spray coater manufactured by Asahi Sunac under the conditions shown in Table 1. The liquid feeding amount at this time was 10 ml / min. Further, the substrate was dried at a surface temperature of 120 ° C. to provide a light emitting layer. When the coating was performed under the same conditions on a separately prepared substrate and measured, the film thickness was 40 nm. Moreover, the time required for the coating to be performed under the same conditions on another substrate and the residual solvent ratio to be 5 wt% or less was 30 minutes.
(Light emitting layer coating solution)
Butyl acetate 100g
HA 0.1g
DA 0.011g
DB 0.002g
DC 0.002g

[Production of Organic EL Element 13] (Comparative Example)
When the light emitting layer was applied, the organic EL element 13 was prepared in the same manner as the organic EL element 12 except that the light emitting layer coating liquid was changed to the following coating liquid and the conditions shown in Table 1 were used.
(Light emitting layer coating solution)
Toluene 100g
HA 1g
DA 0.11g
DB 0.002g
DC 0.002g

<Evaluation>
The evaluation of the organic EL elements 1 to 13 produced as described above is disclosed. The main points of the evaluation results of each evaluation item are summarized in Table 2.

(1) Deposition rate
The base material was transported, and the film forming speed was calculated at a transport speed at which a light emitting layer of 40 nm can be formed with 1 Pass.
The ranking was performed as follows.
5: 3 ≦ Conveying speed 4; 2 ≦ Conveying speed <3
3: 1≤Conveying speed <2
2 0.1 ≦ Conveying speed <1
1: Conveying speed <0.1

(2) In-plane uniformity [Measurement of in-plane brightness uniformity and in-plane chromaticity distribution]
When each organic EL element is driven at 5 V using a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing), luminance and chromaticity are measured in a mesh shape at intervals of 5 mm from a position 5 mm from the end of the light emitting region. The luminance uniformity and chromaticity distribution were determined by the following formula.
Luminance uniformity = Lmin / Lmax × 100
Lmax: Maximum value of measured luminance Lmin: Minimum value of measured luminance
In Table 2, the obtained calculation results are shown in the following ranks.
5: Luminance uniformity ≧ 85%, small variation in luminance is very preferable 4: 85%> Brightness uniformity ≧ 70%,
3: 70%> luminance uniformity ≧ 60%,
2: 60%> Luminance uniformity ≧ 50%
1: 50%> Brightness uniformity, brightness varies.

(3) Lifetime A current that gives a front luminance of 1000 cd / m @ 2 was applied to the produced organic EL device, and the device was continuously driven. The time required for the front luminance to reach the initial half value (500 cd / m 2) is obtained, and the light emission lifetime of the organic EL elements 1 to 9 is defined as 100 when the measured value of the organic EL element 1 (comparative) is used. Evaluation was made by EL life of each element) / (life of organic EL element 1). In Table 2, the obtained calculation results are shown in the following ranks.
3: 0.9 <lifetime
2: 0.5 <lifetime ≦ 0.9
1: Life ≤ 0.5

(4) Layer mixing amount Using a scanning X-ray photoelectron spectrometer (PHI 5000) manufactured by ULVAC-PHI, the layer mixing amount was measured by the following method.
1. Under various conditions, first, only a light emitting layer is deposited to 40 nm on a glass substrate.
2. After film formation, sputter using PHI-5000 until the glass component is detected by Ar gas cluster ions. The sputtering time t at that time is obtained.
Thereby, the film thickness can be estimated from the sputtering time.
3. A light emitting layer is formed under the same conditions as 1 on the substrate on which the successful transport layer has been formed.
4. Sputtering is performed in the same manner as in step 2, but at this time, the hole transport layer is sputtered for a sputtering time t or longer.
5. If the amount of Ir contained in the light-emitting layer is not contained in the hole-transporting material in the hole-transporting layer, the amount of layer mixture can be grasped.
If the depth is sputtered until Ir disappears, the film thickness of the layer mixture can be estimated from the sputtering time.
In addition, the layer mixing amount was ranked as follows.
3: Mixing amount of light emitting layer and hole transport layer <2 nm
2: 2 nm ≦ layer mixing amount of light emitting layer and hole transport layer <10 nm
1: 10 nm ≦ layer mixing amount of light emitting layer and hole transport layer

(5) Material yield The material yield represents the ratio between the amount of mist W applied from the nozzle and the amount of mist Wt adhering to the substrate, and is expressed as follows.
Material yield = Wt / W x 100%
The amount of mist adhering to the substrate is determined from the solid content concentration of the liquid and the average film thickness d (measured at 10 mm intervals) at 81 locations of the film adhering to the 100 mm x 100 mm x 1.1 t glass substrate. Calculated from the formula
* Weight of attached film (g) = 10 x 10 x d (cm) x density of solid material (g / cm3)
Wt = weight of attached film (g) / solid concentration of liquid (%) × 100
W = Time when the nozzle was on the substrate (min) x Mist generation (g / min)
In Table 2, the obtained calculation results are shown in the following ranks.
5: Material yield> 85%
4:75 <material yield ≦ 85%
3: 65 <Material yield ≦ 75%
2: 50 <material yield ≦ 65%
1: Material yield ≦ 50

(6) Residual solvent amount Here, the measurement of the residual solvent ratio according to the present example is shown below. A headspace type gas chromatographic determination method is used.
The headspace type gas chromatograph used as a method for quantifying the residual solvent contained in the organic layer of the organic EL device of this example uses a detection method such as an internal standard method used in a normal gas chromatograph. And measure.
In the headspace type gas chromatograph quantitative method, the organic EL element is sealed in an open / closed container, heated, and immediately filled with residual solvent (organic solvent and / or water, etc.) in the container. Gas is injected into the gas chromatograph to measure the amount of residual solvent, and MS (mass spectrometry) is also performed.

Hereinafter, the measurement method using the head space type gas chromatograph used in this example will be described in detail.
<Headspace gas chromatograph measurement method>
1. Sample collection Sample organic EL elements in a 20 ml headspace vial. The sample amount is weighed to 0.01 g (necessary for calculating the area per unit mass). Seal the vial with a septum using a dedicated crimper.
2. Heating the sample Place the sample in a 170 ° C constant temperature bath and heat for 30 minutes.
3. Setting of gas chromatographic separation conditions A column coated with silicon oil SE-30 so as to have a mass ratio of 15% and packed in a column having an inner diameter of 3 mm and a length of 3 m is used as a separation column. The separation column is attached to a gas chromatograph, and He is used as a carrier to flow at 50 ml / min.
The temperature of the separation column is set to 40 ° C., and measurement is performed while the temperature is increased to 260 ° C. at a temperature increase rate of 15 ° C./min. Hold for 5 minutes after reaching 260 ° C.
4). Introduction of sample The vial bottle is taken out from the thermostatic chamber, immediately 1 ml of gas generated from the sample is collected with a gas tight syringe, and this is injected into the separation column.
5. Calculation A calibration curve is prepared in advance using the aromatic hydrocarbon compound used as the internal reference material, and the concentration of each component is determined.
6). Equipment (1) Headspace conditions Headspace device HP 769 “Head Space Sampler” manufactured by Hewlett-Packard Company
Temperature conditions Transfer line: 200 ° C
Loop temperature: 200 ° C
Sample amount: 0.8 g / 20 ml vial (2) GC / MS conditions GC: HP5890 manufactured by Hewlett-Packard Company
MS: HP5971 manufactured by Hewlett-Packard Company
Column: HP-624 30m x 0.25mm
Oven temperature: 40 ° C (3 minutes) -15 ° C / minute-260 ° C
Measurement mode: SIM

The present invention can be used for the production of organic thin films such as organic electroluminescence (EL) elements and organic thin film solar cells.

DESCRIPTION OF SYMBOLS 1 Electrostatic spray apparatus 2 Base material 10 Chamber 11 Solution 12 Aerosol 13 Charged fine particle 20 Conveyance path (pipe)
30 Nozzle 33 Discharge port 40 Conveying device (conveying means)
44 Carrier gas 50 Substrate support moving device (support means)
50A roller transport device (support means)

Claims (9)

1. In an electrostatic spray apparatus that forms an organic thin film on a substrate using an electrostatic spray method,
   Aerosol generating means for generating an aerosol in which charged fine particles including an organic material are dispersed;
   A chamber for storing the aerosol generated by the aerosol generating means;
   A transfer path having one end connected to the chamber;
   A nozzle provided at the other end of the transport path;
   Transport means for transporting the aerosol from the chamber to the nozzle through the transport path;
   Supporting means for supporting the base material and holding the base material with a potential difference from the potential of the fine particles,
   An electrostatic spraying apparatus characterized in that fine particles in aerosol sprayed by the nozzle are attracted to the substrate by electrostatic attraction to form the organic thin film.
2. The electrostatic spray device according to claim 1, wherein the chamber includes a plurality of the aerosol generating means.
3. The aerosol generation means, the chamber, and the one end portion are provided in a plurality of sets, and the conveyance path includes a joining portion that joins between the one end portion and the other end portion of each set. The electrostatic spray apparatus of Claim 1 or Claim 2.
4. 4. The apparatus according to claim 1, further comprising a voltage applying unit that applies a voltage to the transport path and charges a surface of the transport path that transports the microparticles to the same charge as the microparticles. 5. The electrostatic spray device described.
5. The electrostatic spray device according to any one of claims 1 to 4, wherein the substrate is held on a stage to which a voltage is applied.
6. The electrostatic spray device according to any one of claims 1 to 5, further comprising a moving unit that relatively moves at least one of the substrate and the nozzle.
7. The electrostatic spray apparatus according to any one of claims 1 to 6, wherein the base material is a belt-like base material.
8. The electrostatic spray apparatus according to any one of claims 1 to 7, wherein the organic thin film is an organic thin film of an organic electroluminescence element.
9. The electrostatic spray device according to claim 8, wherein the organic thin film of the organic electroluminescence element is a light emitting layer.

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