JP5182225B2 - Method for manufacturing organic electroluminescence element - Google Patents

Description

  The present invention relates to an organic electroluminescence element, a display device using the element, a lighting device, and a method for manufacturing an organic electroluminescence element.

  As a light-emitting electronic display device, there is an electroluminescence display (hereinafter abbreviated as ELD). As an ELD component, an inorganic electroluminescence element (hereinafter also referred to as an inorganic EL element) and an organic electroluminescence element (hereinafter also referred to as an organic EL element) can be given. Inorganic EL elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  On the other hand, an organic electroluminescence device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and excitons (excitons) by injecting electrons and holes into the light emitting layer and recombining them. Is a device that emits light by using light emission (fluorescence / phosphorescence) when this exciton is deactivated, and can emit light at a voltage of several V to several tens of V, and further self-emission. Since it is a type, it has a wide viewing angle, high visibility, and since it is a thin-film type completely solid element, it has attracted attention from the viewpoints of space saving, portability, and the like.

  Another major feature of the organic electroluminescence element is that it is a surface light source, unlike main light sources that have been put to practical use, such as light-emitting diodes and cold-cathode tubes. Applications that can effectively utilize this characteristic include illumination light sources and various display backlights. In particular, it is also suitable to be used as a backlight of a liquid crystal full color display whose demand has been increasing in recent years.

  These organic EL device manufacturing methods include a vacuum deposition method, a wet process (coating method), etc., but in recent years a wet process is not required because a vacuum process is not required, continuous production is simple, and production speed can be increased. A manufacturing method in (spin coating method, casting method, ink jet method, spray method, printing method, slot type coater method) has attracted attention.

  In general, examples of the coating type organic EL element include a coating type polymer organic EL element using a polymer material for a light emitting layer (see, for example, Patent Document 1).

  However, in the coating type polymer organic EL device, there are concerns in terms of performance and production stability because it is difficult to purify the material and it is difficult to control the molecular weight distribution. ing.

  Therefore, in recent years, a coating type low molecular organic EL element has attracted attention. A low-molecular organic EL element formed by coating is disclosed (for example, see Patent Document 2), and a low-molecular organic EL element having good color purity, excellent luminous efficiency, luminance, and half-life is provided. However, the coating-type low-molecular organic EL element is not sufficient for use in lighting applications, and further reduction in driving voltage and improvement in life are required.

  The cause of increasing the driving voltage of the low molecular weight coating type organic EL element is the presence of microcrystals contained in the thin film. Films deposited by a general vapor deposition method and polymer films formed by a wet process are known to be amorphous, and the problem of the presence of microcrystals in the thin film is a low molecular coating type organic EL. This is a problem specific to the device.

  In the presence of microcrystals, the transport of holes and electrons is scattered by the grain boundaries, increasing the resistance. In addition, when an organic electroluminescence device containing microcrystals is driven for a long time, the microcrystals grow into larger crystals due to the generation of Joule heat, and the transport resistance of holes and electrons increases with the passage of time. As a result, the device life is shortened. The effect of increasing the driving voltage due to the formation of microcrystals and shortening the device lifetime increases as the crystal size increases. Therefore, in order to reduce the driving voltage of the low molecular weight coating type organic EL element, it is necessary to reduce the size of the contained microcrystals as much as possible and to reduce the number of the microcrystals contained.

  There are a number of prior documents describing coating film formation methods that suppress the inclusion of large crystallites.

  For example, an amorphous thin film forming method by an ink jet coating method is disclosed. By mixing two kinds of solvents and ensuring the optimum ink viscosity, and increasing the surface tension of the ink in the drying process and the solubility limit of the organic material, the ink jet can be selectively applied only to the concave area partitioned by the partition wall layer. A method of forming an amorphous film of an organic material by a method is disclosed (for example, see Patent Document 3).

  Although this method can be said to be effective for the whole coating method, the confirmation of the formation of an amorphous film in this document is performed only by visual observation, and the possibility of generating microcrystals in an invisible range cannot be denied. .

  In addition, after applying the organic layer material in an inert gas atmosphere, in an inert gas atmosphere, heat drying is performed at a temperature lower than the glass transition temperature Tg by 10 ° C. or more, thereby crystallization of organic matter during heating is performed. A method for preventing this is disclosed (for example, see Patent Document 4).

  In this method, crystal growth at the time of heat drying can be prevented, but the formation of large crystallites due to the volatilization of the solvent that occurs from the time of application to the time of heat drying is unavoidable.

  Furthermore, there is a document (for example, see Patent Document 5) that discloses a method for manufacturing a vapor deposition type organic EL element including a thin film in which a diffraction peak due to microcrystals is not detected by X-ray diffraction. A method for producing a low molecular weight coating type organic EL element in which no peak is detected remains as an unsolved problem.

JP-A-6-33048 JP 2006-190759 A JP 2006-66294 A JP-A-2005-310639 JP 2005-276748 A

An object of the present invention, the power efficiency is high and a long life, is to provide a method for manufacturing an organic EL element microcrystals emitting layer of the element is not contained.

  The above object of the present invention has been achieved by the following constitution.

1. Anode, as a layer between a cathode, and at least one layer producing method of an organic electroluminescence element having a luminescent layer of which contains a dopant and a host, the light emitting layer is deposited by a coating method, at least a light emitting layer One layer is a light emitting layer made of a low molecular organic compound, and the light emitting layer has a drying time of 20 seconds or less until the film thickness increases by 5% of the final film thickness after coating, film formation and drying of the light emitting layer. and a step of forming a and method of producing an organic electroluminescent device X-ray diffraction peak due to crystallites of the low-molecular organic compound of the light emitting layer is equal to or not detected.

2. 2. The method for producing an organic electroluminescent element according to 1 above, wherein the host has a molecular weight of 1500 or less.

3. 3. The method for producing an organic electroluminescence device according to 1 or 2, wherein the host has a molecular weight of 800 or less.

4). 4. The method for producing an organic electroluminescent element according to any one of 1 to 3, wherein the host has at least three partial structures represented by the following general formula (a) in one molecule.

[Wherein X represents NR ′, O, S, CR′R ″ or SiR′R ″. R ′ and R ″ each represent a hydrogen atom or a substituent. Ar represents an atomic group necessary for forming an aromatic ring. N represents an integer of 0 to 8.]
5. Method of manufacturing an organic electroluminescent device according to any one of the 1-4, wherein the dopant is characterized in that exhibits phosphorescence.

6). 6. The method for producing an organic electroluminescent element according to 5 above, wherein the dopant is represented by the following general formula (1).

[Wherein, Z represents a hydrocarbon ring group, an aromatic heterocyclic group or a heterocyclic group. R _{81 to} R ₈₆ each represent a hydrogen atom or a substituent. P ₁ -L ₁ -P ₂ represents a bidentate ligand, and P ₁ and P ₂ each independently represent a carbon atom, a nitrogen atom or an oxygen atom. L1 represents an atomic group forming a bidentate ligand together with P ₁ and P ₂ . j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, and j1 + j2 is 2 or 3. M ₁ represents a group 8-10 metal element in the periodic table. ]
7). 7. The method for producing an organic electroluminescent element according to 6 above, wherein M _{1 in the} general formula (1) is iridium.

8 . 8. The method for producing an organic electroluminescent element according to any one of 1 to 7, wherein the drying time is 10 seconds or less.

The present invention, power-efficient, and long life, microcrystalline the light emitting layer of the element is able to provide a manufacturing how the organic EL element not contained.

It is a schematic diagram which shows an example of the coating device applied to the manufacturing method of the organic EL element of this invention. It is a side surface enlarged view of the coating device shown in FIG. It is a schematic plan view which shows an example of the installation arrangement | sequence of the inkjet head 311 used for the coating device shown in FIG.

In the manufacturing method of the organic electroluminescence element of the present invention, the structure as defined in any one of claims 1-8, showed high power efficiency, and, in the long organic electroluminescent device emission lifetime, together It was possible to provide a method for producing an organic EL device in which no microcrystal is contained in the light emitting layer of the device .

  Hereinafter, details of each component according to the present invention will be sequentially described.

The present invention provides an organic electroluminescent device having an anode and a cathode on a substrate, and having at least one light emitting layer containing a dopant and a host as a constituent layer on the anode and the cathode.
(A) The light emitting layer is formed by a coating method,
(B) The said light emitting layer is an organic electroluminescent element which does not contain the microcrystal measured by X-ray diffraction.

  The organic EL device of the present invention has dramatically improved power efficiency as compared with a low molecular weight coating type organic electroluminescence device containing a coating film of a light emitting layer in which microcrystals are detected by conventionally known X-ray diffraction. It has been found that the service life is extended.

  Hereinafter, the details of each component of the organic electroluminescence element of the present invention (hereinafter also referred to as the organic EL element of the present invention) will be sequentially described.

<< Layer structure of organic EL element >>
Next, although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.

(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 << Formation method of each of the above layers >>
In the organic electroluminescence device of the present invention, it suffices that at least one light emitting layer as a constituent layer is formed by a coating method, and the formation method of the other layers is not particularly limited to the coating film forming method, and is necessary. In accordance with the above, it is also possible to form a film using a vapor deposition method or the like.

  However, in the method for producing an organic EL device of the present invention, a coating method (also referred to as a coating film forming method) is used as a method for forming a light emitting layer that is a constituent layer, and among them, a spin coating method, a casting method, an inkjet method. , Spray method, printing method, slot type coater method, etc., but it is easy to obtain a homogeneous film and it is difficult to generate pinholes, and so on, spin coating method, ink jet method, spray method, printing method, slot Film formation by a coating method such as a mold coater method is preferred, and among these, the slot coater method can be more preferably used.

  Of course, it is preferable to apply the above-described coating method (coating film forming method) also to the constituent layers other than the light emitting layer of the organic EL device of the present invention.

  As a drying method after coating film formation, spin drying, hot air drying, far infrared drying, vacuum drying, reduced pressure drying, and the like can be applied.

(Light-Emitting Layer Coating Method): Formation of Light-Emitting Layer in Which X-Ray Diffraction Peak is not Detected Hereinafter, a light-emitting layer coating method is described in detail as a method for producing the organic EL device of the present invention. In the present invention, the coating film forming method refers to a method from the end of application to the end of drying.

  The present inventors prepared low molecular organic thin films formed so as to have the same film thickness by various coating film forming methods, and suppressed the size and content of contained microcrystals in the low molecular organic thin films. As a result of repeated intensive investigations, a diffraction peak due to low molecular weight organic matter is not detected in X-ray diffraction measurement by shortening the drying time until the final film thickness after drying is increased by 5% after coating. It has been found that a thin film can be formed.

  There are a large number of low-molecular organic substances in the light-emitting layer such as a dopant (also referred to as a light-emitting dopant) and a host (also referred to as a light-emitting host). I can't say how much time should be shortened, but when I checked the conditions for some low molecular weight organic substances, most of them increased 5% of the final film thickness after coating and drying. By setting the drying time to the film thickness to 20 seconds or less, a thin film in which a diffraction peak due to a low molecular organic substance was not detected by X-ray diffraction measurement could be formed.

  It is a thin film with a drying time of 20 seconds or less from coating to the final film thickness of 5% of the final film thickness after drying, and it is a low molecular weight organic material whose diffraction peak is detected by X-ray diffraction measurement. However, by further shortening the drying time to 10 seconds or less, it was possible to form a thin film in which no X-ray diffraction peak was observed.

  From this, the present inventors have inferred that the shorter the drying time, the smaller the size of the microcrystals.

  Incidentally, the present invention is the first to make it possible to use a thin film in which a diffraction peak due to a low molecular organic substance is not detected by X-ray diffraction measurement for a low molecular coating type organic EL device. There are no examples.

  In addition, this time, the present inventors, in the formation of the light emitting layer, in particular, the molecular weight of the host (host compound), the presence or absence of the X-ray diffraction peak of the light emitting layer after coating film formation, and the characteristics of the organic EL element obtained ( It has been found that there is a preferable relationship in relation to power efficiency and light emission lifetime.

  That is, the molecular weight of the low molecular weight organic substance, particularly the host, in the light emitting layer according to the present invention is preferably in the range of 400 to 1500, more preferably in the range of 400 to 800.

  Here, the molecular weight according to the present invention can be obtained using a conventionally known mass spectrum. However, for polymers (for example, those having a molecular weight of 10,000 or more), a conventionally known GPC (gel permeation chromatography) is used. It was measured using.

  In the process of applying and drying a thin film such as a light emitting layer according to the present invention, after the solution is applied, as the thin film is formed and the drying proceeds, the thickness of the film decreases as the solvent evaporates. The solvent does not evaporate, and a thin film having a final film thickness after drying is obtained.

  The film thickness increased by 5% of the final film thickness after drying corresponds to, for example, a film thickness of 52.5 nm when attempting to produce a thin film having a final film thickness after drying of 50 nm. .

  For example, a spectroscopic ellipsometer (for example, UVISEL manufactured by Joban Yvon) can be used to measure the thickness of the light emitting layer according to the present invention.

  Also, there is a coating film forming method for forming a thin film in which a diffraction peak due to a low molecular organic substance is not detected by X-ray diffraction measurement by shortening the drying time until the film thickness is increased by 5% of the final film thickness after drying. The drive voltage of the coating type low molecular organic EL element produced using the driving voltage is higher than that of the coating type low molecular organic EL element formed by the usual coating film forming method in which an X-ray diffraction peak is observed when applied. It has been confirmed that the power efficiency is greatly increased due to the significant decrease in the voltage, which is effective in improving the performance of the low molecular weight coating type organic EL element.

  Further, the performance of the one with the drying time shortened to 10 seconds or less was improved as compared with the other one.

(It does not contain microcrystals measured by X-ray diffraction measurement in the light emitting layer)
For the X-ray diffraction measurement of the light emitting layer, for example, a thin film structure evaluation apparatus ATX-G manufactured by Rigaku Corporation can be used. The measurement conditions are shown below.

  X-rays were generated with a target of copper and an output of 15 kW. Measurement was performed using a slit collimation optical system. The parallel X-rays were made incident at a low angle near the total reflection critical angle, and the penetration depth of the X-rays was made equal to the film thickness.

In the X-ray diffraction measurement of the light emitting layer, the incident angle θ was 0.23 °, the X-ray irradiation area was limited by the size of the slit, and the maximum irradiation area was adjusted to 25 mm ² .

  The incident angle is fixed, the detector is scanned at 2θ = 5 ° to 45 °, and the X-ray intensity is measured. In the X-ray diffraction measurement for confirming crystallinity, at least 3 points, preferably 5 points or more are measured near the center of the target element.

  In the thin film produced by the coating film forming method of the light emitting layer according to the present invention, the fact that no microcrystal is contained in the X-ray diffraction measurement means that no X-ray diffraction peak is observed. In the measurement, when no diffraction peak is observed, no diffraction peak is observed when the crystallinity of the reference compound in the light emitting layer is 1% or less.

  In that case, in this application, it defines that the light emitting layer does not contain the microcrystal measured by X-ray-diffraction measurement.

  The degree of crystallinity refers to the ratio of the crystalline diffraction peak in the total X-ray scattering intensity. X-ray diffraction measurement is performed at least 3 points, preferably 5 points or more, crystallinity is calculated, and crystallinity is determined based on the average.

  The present inventors infer that the mechanism of the microcrystal grains can be reduced by shortening the drying time as follows.

  When the drying time is short, it is considered that the solvent is not sufficiently evaporated from the inside of the film. Since crystals consist of an ordered arrangement of one type of molecule, it can be said that it was difficult to produce fine crystal grains in a system in which a solvent remained. It can be said that the film thickness increased by 5% of the final film thickness after drying corresponds to the film thickness capable of forming a dense film on the film surface.

  From this, the coating film forming method of the light emitting layer according to the present invention may be any drying process as long as the drying time can be shortened. For example, a method in which the drying speed is changed in multiple stages and a method using a combination of various drying means ( For example, a combination of hot air drying and far infrared drying) is also included. Here, the drying speed corresponds to the amount of solvent that evaporates during a unit time.

  The method of controlling the drying speed may be to control the conditions of the drying method such as the temperature and speed of the wind if hot-air drying and the spin rotation speed if spin-drying, and to select a solvent with a different vapor pressure for the coating solution. Although mentioned, the control method of the drying rate used for this invention is not limited to these.

  The solvent that can be used in the present invention preferably has a high drying rate, and more preferably has a vapor pressure at 20 ° C. of 2.67 kPa or more.

  Examples of such a solvent include, but are not limited to, toluene, ethyl acetate, propyl acetate, isopropyl acetate, methyl ethyl ketone, and the like. When hot air drying is performed using a solvent with a high vapor pressure of 2.67 kPa or higher at 20 ° C., the final film thickness after drying after application is reduced while keeping the wind speed in hot air drying small. The drying time up to 5% increase in film thickness can be shortened. Since the wind speed can be kept small, it is possible to reduce uneven blow-off during drying.

  The reason why the power efficiency of the organic EL device produced using the coating and drying method according to the present invention is high is that even if the proportion of the volume contained by the microcrystals in the thin film is the same, the microcrystals are small in size. Compared to the case where large crystallites are included, the probability that the carriers encounter the interface between the amorphous film and the microcrystal grains during driving of the element can be lowered, so that the carriers are less likely to be scattered. ing.

  In addition, a method for forming other constituent layers other than the light emitting layer of the organic EL device of the present invention will be described in detail in the method for manufacturing the organic EL device described later.

<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 film thickness of the light emitting layer is not particularly limited, but it is 2 from the viewpoint of the uniformity of the film to be formed, the application of unnecessary high voltage during light emission, and the improvement of the stability of the emission color with respect to the drive current. It is preferable to adjust to the range of -200 nm, More preferably, it adjusts to the range of 5 nm or more and 100 nm or less.

  The light emitting layer of the organic electroluminescence element of the present invention is preferably formed by a wet process. Known wet process coating methods include spin coating, casting, ink jet, spraying, printing, slot coater, etc., but it is easy to obtain a uniform film and pinholes are not easily generated. In view of the above, in the present invention, film formation by a coating method such as a spin coating method, an ink jet method, a spray method, a printing method, a slot type coater method is preferable, and among these, a slot type coater method is more preferable.

  Moreover, it is preferable that the light emitting layer of an organic electroluminescent element contains at least 1 type of a light emission host and a light emission dopant from the point of luminous efficiency improvement.

  Hereinafter, the dopant and host contained in the light emitting layer will be described.

(host)
Here, the host in the present invention is a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.1 at room temperature (25 ° C.) among compounds contained in the light emitting layer. The phosphorescence quantum yield is preferably less than 0.01. Moreover, it is preferable that the mass ratio in the layer is 20% or more among the compounds contained in a light emitting layer.

  There is no restriction | limiting in particular as a host which can be used for this invention, Although the compound conventionally used with an organic electroluminescent element can be used, it has a hole transport ability and an electron transport ability, and is a big excitation triplet energy. And a compound having a high Tg (glass transition temperature) is preferable.

  Further, a plurality of types of hosts may be used in combination. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the efficiency of the organic EL element can be further increased. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and thereby, arbitrary light emission colors can be obtained.

  The host used in the present invention may be a high molecular compound or a low molecular compound. Among the low molecular compounds, a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (polymerizable light emitting host). But you can. Moreover, you may use 1 type or multiple types of such a compound.

  The molecular weight of the host compound (also simply referred to as a host) according to the present invention is preferably 1500 or less, and more preferably 800 or less.

  As the luminescent host, a known luminescent host may be used alone, or a plurality of luminescent hosts may be used in combination. By using a plurality of types of light-emitting hosts, the movement of charges can be adjusted, and the efficiency of the organic electroluminescence element can be improved. Moreover, it becomes possible to mix different light emission by using multiple types of light emission dopants mentioned later, and, thereby, arbitrary luminescent colors can be obtained.

  As the known light-emitting host that may be used in combination, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from becoming longer, and has a high Tg (glass transition temperature) is preferable.

  Specific examples of the known light-emitting host include compounds described in the following documents.

  JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  Among them, the host compound according to the present invention is preferably a host compound having at least three partial structures represented by the general formula (a). Three or more connections may be connected at the X portion or at other portions.

<< Partial structure represented by general formula (a) >>
The partial structure represented by the general formula (a) will be described.

  In X of the partial structure represented by the general formula (a), the substituents represented by R ′ and R ″ may be alkyl groups (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group). Group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.) ), Alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, Xylyl, naphthyl, anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, in Nyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1, 2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, A quinolyl group, a benzofuryl group, a dibenzofuryl group, a benzothienyl group, a dibenzothienyl group, an indolyl group, a carbazolyl group, a carbolinyl group, a diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is a nitrogen atom ), Quinoxalinyl group, Ridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyl) Oxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (Eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, For example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, Phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group) , Dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, aceto Group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group ( For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonyl) Amino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcal Nylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexyl) Aminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido) Group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridy Sulfinyl group (eg, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group) Group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenyl) Sulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino) Group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom), fluorinated hydrocarbon Group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, Triphenylsilyl group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. A plurality of these substituents may be bonded to each other to form a ring.

  Among these, X is preferably NR ′ or O, and R ′ is an aromatic hydrocarbon group (also called an aromatic carbocyclic group or aryl group, such as phenyl group, p-chlorophenyl group, mesityl group, tolyl group). Group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group) or aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group) , Pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group and the like are particularly preferable.

  The above aromatic hydrocarbon group and aromatic heterocyclic group each may have a substituent represented by R ′ or R ″ in X of the partial structure represented by the general formula (a). .

  In the partial structure represented by the general formula (a), examples of the aromatic ring represented by Ar include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. The aromatic ring may be a single ring or a condensed ring, and may be unsubstituted, or may have a substituent represented by each of R ′ and R ″ in X of the partial structure represented by the general formula (a). May be.

  In the partial structure represented by the general formula (a), the aromatic hydrocarbon ring represented by Ar includes a benzene ring, a biphenyl ring, a naphthalene ring, an azulene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysene ring, Naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, Examples include a picene ring, a pyrene ring, a pyranthrene ring, and an anthraanthrene ring. These rings may further have substituents each represented by R ′ and R ″ in X of the partial structure represented by the general formula (a).

  In the partial structure represented by the general formula (a), examples of the aromatic heterocycle represented by Ar include a furan ring, a dibenzofuran ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, and a pyrimidine ring. , Pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline Ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) Etc.) It is below.

  These rings may further have substituents represented by R ′ and R ″ in X of the partial structure represented by the general formula (a).

  Among the above, in the general formula (a), the aromatic ring represented by Ar is preferably a carbazole ring, a carboline ring, a dibenzofuran ring, or a benzene ring, and more preferably a carbazole ring, A carboline ring and a benzene ring, more preferably a benzene ring having a substituent, and particularly preferably a benzene ring having a carbazolyl group.

  In the general formula (a), the aromatic ring represented by Ar is preferably a condensed ring having 3 or more rings, and the aromatic hydrocarbon condensed ring in which 3 or more rings are condensed is a specific example. Naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring, triphenylene ring, coronene ring, benzocoronene Ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthoperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyrantolen ring, coronene ring, naphthocolonene ring, ovalen ring, Anthracanthrene ring, etc. And the like.

  In addition, these rings may further have the above substituent.

  Specific examples of the aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, A Tiger thiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, such as thio fan Tren ring (naphthaldehyde thiophene ring), and the like. In addition, these rings may further have a substituent.

  In the general formula (a), n represents an integer of 0 to 8, preferably 0 to 2, particularly preferably 1 to 2 when X is O or S.

<< Host compound represented by general formula (a-1), (a-2) or (a-3) >>
The host compound according to the present invention has at least three partial structures represented by the above general formula (a). Preferred embodiments include the following general formulas (a-1), (a-2) or (a The compound represented by -3) is preferable.

  In the formula, Ar ′ and Ar ″ represent an aromatic ring, and the aromatic ring has the same meaning as the aromatic ring represented by Ar in the general formula (a). N represents an integer of 1 or more, and m represents 0 or more. Represents an integer.

《Dopant》
Next, the dopant will be described.

  There are two possible light emission principles of the dopant-host type. One is that the recombination of carriers occurs on the host to which carriers are transported to generate an excited state of the host compound, and this energy is transferred to the dopant. It is an energy transfer type that obtains light emission from a dopant. The other is a carrier trap type in which the dopant becomes a carrier trap, and carrier recombination occurs on the dopant compound, and light emission from the dopant is obtained.

  In the energy transfer type, it is preferable that the overlap integral between the emission of the host and the absorption of the dopant is large as a condition for easy energy transfer. The carrier trap type needs to have an energy relationship that facilitates carrier trapping. For example, the electron carrier trap needs to have a dopant electron affinity (LUMO) greater than the host electron affinity (LUMO level).

  Conversely, the hole carrier trap preferably has a dopant ionization potential (HOMO) smaller than the dopant ionization potential (HOMO).

  For these reasons, the dopant can be selected from the emission color including the color purity and the emission efficiency, and the host compound is selected from those having good carrier transportability and satisfying the above energy relationship.

  The dopant of the light emitting layer can be selected from known ones used as the dopant of the organic EL element, but is preferably an organic compound or complex that emits fluorescence or phosphorescence.

  Representative examples of fluorescent dopants include compounds with high fluorescence quantum yields such as laser dyes, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes. Fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes, polythiophene dyes, rare earth complex phosphors, and the like.

  The dopant that emits phosphorescence is a compound in which light emission from an excited triplet is observed, specifically, a compound that emits phosphorescence at room temperature (25 ° C.), and a phosphorescence quantum yield of 25 ° C. However, a preferable phosphorescence quantum yield is 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence dopant according to the present invention achieves the phosphorescence quantum yield (0.01 or more) in any solvent. That's fine.

  The phosphorescent dopant according to the present invention 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 europium complex, or a platinum compound (platinum complex system). Compound) and rare earth complexes, and most preferred is an iridium compound.

  More preferably, the phosphorescent dopant according to the present invention includes a compound represented by the general formula (1). Specific examples include compounds described in the following patent publications.

  WO 00/70655 pamphlet, JP 2002-280178, JP 2001-181616, JP 2002-280179, JP 2001-181617, JP 2002-280180, JP 2001-247859, JP 2002-299060, JP 2001-313178, JP 2002-302671, JP 2001-345183, JP 2002-324679, International Publication No. 02/15645 pamphlet, JP 2002-332291 A, JP 2002-50484 A, JP 2002-332292 A, JP 2002-83684 A, JP 2002-540572 A, JP 2002-2002 A. No. 117978, JP 20 JP-A-2-338588, JP-A-2002-170684, JP-A-2002-352960, WO01 / 93642, JP-A-2002-50483, JP-A-2002-1000047, JP-A-2002. No. -173744, JP-A No. 2002-359082, JP-A No. 2002-17584, JP-A No. 2002-363552, JP-A No. 2002-184582, JP-A No. 2003-7469, JP-T-2002-525808. Gazette, JP2003-7471, JP2002-525833, JP2003-31366, JP2002-226495, JP2002-234894, JP2002-2335076 JP 2002-241751 A JP 2001-319779, JP 2001-319780, JP 2002-62824, JP 2002-1000047, JP 2002-203679, JP 2002-343572, JP 2002-203678 gazette etc.

  Although the example of a dopant is given to the following, it is not limited to these.

  In particular, when a phosphorescent dopant is used in the organic EL device of the present invention, the triplet energy of the host is preferably larger than the triplet energy of the dopant. Thereby, brightness | luminance and external extraction efficiency can be made high, and quality can be improved more.

  As the phosphorescent dopant according to the present invention, a compound represented by the above general formula (1) is preferably used.

In the general formula (1), examples of the bidentate ligand represented by P ₁ -L ₁ -P ₂ include substituted or unsubstituted phenyl pyridine, phenyl pyrazole, phenyl imidazole, phenyl triazole, phenyl tetrazole, and pyraza ball. Acetylacetone, picolinic acid and the like.

As M ₁ , a transition metal element belonging to Group 8 to 10 in the periodic table of elements is used, among which iridium and platinum are preferable, and iridium is particularly preferable.

  Examples of the hydrocarbon ring group represented by Z include a non-aromatic hydrocarbon ring group and an aromatic hydrocarbon ring group. Examples of the non-aromatic hydrocarbon ring group include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group. And may be substituted or unsubstituted.

  Examples of the aromatic hydrocarbon ring group (also referred to as aromatic hydrocarbon group, aryl group, etc.) include, for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl. Group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group and the like. These groups may be substituted or unsubstituted.

In the general formula (1), R _{81 to} R ₈₆ represent a hydrogen atom or a substituent. Examples of the substituent include R ′ and R ″ in X of the partial structure represented by the general formula (a) described above. And the same as the substituents represented by each.

  In addition, these substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

  Next, an injection layer, a blocking layer, an electron transport layer, and the like used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer can be provided as necessary, and may exist 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.

  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), 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 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.

  Further, ferrocene compounds described in JP-A-6-025658, starburst type compounds described in JP-A-10-233287, JP-A-2000-068058, JP-A-2004-6321 Triarylamine type compounds described in JP-A-2002-117799, sulfur-containing ring-containing compounds described in JP-A No. 2002-1171979, US Patent Application Publication No. 2002/158242, US Patent Application Publication No. 2006 / Examples of the hole injection layer include hexaazatriphenylene compounds described in Japanese Patent No. 251922, Japanese Patent Application Laid-Open No. 2006-49393, and the like.

  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 or aluminum Metal buffer layer represented by lithium fluoride, alkali metal compound buffer layer represented by lithium fluoride, alkaline earth metal compound buffer layer represented by magnesium fluoride, oxide buffer layer represented by aluminum oxide, etc. It is done.

  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 as a constituent layer of the organic compound thin film.

  For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking.

  Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.

  When the hole blocking layer of the organic EL device of the present invention is provided adjacent to the light emitting layer, it is preferably formed by a wet process. Furthermore, it is particularly preferably formed by a coating method such as an ink jet method, a printing method, or a slot type coater method, and among these, it is more preferable to form by a slot type coater method.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material having a function of transporting holes while having a very small ability to transport electrons, and transporting electrons while transporting holes. By blocking, the recombination probability 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 concerning this invention as needed.

  The thickness of the hole blocking layer and the electron blocking layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm 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, the hole injection layer and the electron blocking layer also have the function of a hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material has any one of hole injection or transport and 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 ' − (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 condensations described in US Pat. No. 5,061,569 Those having an aromatic ring in the molecule, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-30868 No. 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) in which three triphenylamine units described in the publication No. 1 are linked in a starburst type ) And the like.

  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, 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.

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

  The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a wet process method, a printing method including an inkjet method, a spray method, a slot type coater method, or the like. However, in the case where it is provided adjacent to the light emitting layer, it is preferably formed by a wet process. Furthermore, it is particularly preferably formed by a coating method such as an ink jet method, a printing method, a slot type coater method, etc., and among them, it is more preferable to form by a slot type coater method.

  Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of two or more of the above materials.

  Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J. Pat. 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, the electron injection layer and the hole blocking layer also have a function of the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, as an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the cathode side with respect to the light emitting layer, it has a function of transmitting electrons injected from the cathode to the light emitting layer. As the material, any one of conventionally known compounds can be selected and used. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide 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 (Alq), 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. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and an inorganic semiconductor such as n-type-Si, n-type-SiC, etc. as in the case of the hole injection layer and the hole transport layer. Can also be used as an electron transporting material.

  The electron transport layer is 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 inkjet method, a spray method, a slot type coater method, or the like. However, when it is provided adjacent to the light emitting layer, it is preferably formed by a wet process. Furthermore, it is particularly preferably formed by a coating method such as an ink jet method, a printing method, a slot type coater method, etc., and among them, it is more preferable to form by a slot type coater method.

  Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The electron transport layer may have a single layer structure composed of two or more of the above materials.

"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 electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming 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 so high (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. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also 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 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low 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 (Al ₂ O ₃ ) Mixtures, 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 (Al ₂ O ₃ ) 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 a 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 one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal with a film thickness of 1-20 nm on a cathode, a transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

《Support substrate》
As a support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film capable of giving flexibility to the organic EL element.

  Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) 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, polyether ketone imide, polyamide, fluorine resin, nylon, polymethyl methacrylate, acrylic or polyarylates, and cycloolefin resins such as ARTON (manufactured by JSR) or APEL (manufactured by Mitsui Chemicals).

An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and a barrier film having a water vapor permeability of 0.01 g / m ² / day · atm or less is preferable. Furthermore, a high barrier film having an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less is preferable.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  The method for forming the barrier film is not particularly limited. For example, the 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 weight A combination method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, and the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

  Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.

  The external extraction quantum efficiency at room temperature of light emission of the organic electroluminescence device of the present invention is preferably 1% or more, more preferably 5% or more.

  Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support substrate with an adhesive agent can be mentioned, for example.

  As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.

  Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

  In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned.

Furthermore, the polymer film oxygen permeability measured by the method based on JIS K 7126-1987 is ^{1 × 10 -3 ml / m 2} / 24h or less, as measured by the method based on JIS K 7129-1992, water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is preferably that of ^{1 × 10 -3 g / (m} 2 / 24h) or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

  Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

  In addition, since an organic electroluminescent element may deteriorate with heat processing, what can be adhesively cured from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

  In addition, it is also preferable that the electrode and the organic layer are coated on the outside of the electrode facing the support substrate with the organic layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can.

  Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. 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 A plasma polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil can be injected in the gas phase and liquid phase. preferable. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.

  Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, and the like), and anhydrous salts are preferably used in sulfates, metal halides, and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided on the outer side of the sealing film on the side facing the support substrate with the organic layer interposed therebetween or on the sealing film. In particular, when the sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used. It is preferable to use a film.

《Light extraction》
The organic EL element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1) and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because the light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the element side surface.

  As a method for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (US Pat. No. 4,774,435), A method of improving efficiency by providing a light collecting property to a substrate (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on a side surface of an element (Japanese Patent Laid-Open No. 1-220394), and light emission from a substrate A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between the bodies (Japanese Patent Laid-Open No. 62-172691), a flat having a lower refractive index between the substrate and the light emitter than the substrate A method of introducing a layer (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283951) Gazette).

  In the present invention, these methods can be used in combination with the organic EL device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

  In the present invention, by combining these means, it is possible to obtain an element having higher luminance or durability.

  When a medium having a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower.

  Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and a fluorine-based polymer. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.

  The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

  The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by first-order diffraction, second-order diffraction, and Bragg diffraction. Light that cannot be emitted due to total internal reflection between layers is diffracted by introducing a diffraction grating in any layer or medium (in a transparent substrate or transparent electrode), and the light is removed. I want to take it out.

  The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.

  As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or in the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

  At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

  The arrangement of the diffraction grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condenser sheet>
The organic EL device of the present invention is processed on the light extraction side of the substrate so as to provide, for example, a microlens array structure, or combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the device light emitting surface. By condensing in the front direction, the luminance in a specific direction can be increased.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  As the condensing sheet, for example, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, Sumitomo 3M brightness enhancement film (BEF) can be used. As the shape of the prism sheet, for example, the base material may be formed by forming a △ -shaped stripe having a vertex angle of 90 degrees and a pitch of 50 μm, or the vertex angle is rounded and the pitch is changed randomly. Other shapes may be used.

  Moreover, in order to control the light emission angle from a light emitting element, you may use together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate so as to have a thickness of 1 μm or less, preferably 10 nm to 200 nm, to form an anode.

  After the production, a cleaning surface modification treatment step and a charge removal treatment step may be performed.

  As the cleaning surface modification treatment, a low-pressure mercury lamp, an excimer lamp, a plasma cleaning apparatus, or the like can be used. By this cleaning surface modification treatment, surface modification for removing organic contaminants and improving wettability is performed.

  The charge removal treatment is roughly classified into a light irradiation method and a corona discharge method, and the light irradiation method generates weak ions and the corona discharge method generates air ions by corona discharge. The air ions are attracted to the charged object to compensate for the opposite polarity charge and neutralize static electricity.

  A static eliminator using corona discharge or a static eliminator using soft X-rays can be used. By this electrification removal process, the substrate is de-charged, so that dust adhesion and dielectric breakdown are prevented, so that the yield of the elements can be improved.

  Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, is formed thereon.

  As described above, the organic layer of the organic EL device of the present invention is formed by a vacuum deposition method and a wet process (spin coating method, casting method, ink jet method, spray method, printing method, slot type coater method). From the point that a film is easily obtained and pinholes are difficult to be generated, in the present invention, a part or all of the organic layer is subjected to a spin coating method, an ink jet method, a spray method, a printing method, a slot type coater method, etc. Film formation by a wet process is preferable, and among these, the slot type coater method is more preferable.

  Examples of the liquid medium for dissolving or dispersing the organic electroluminescent material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate and butyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, and the like. Aromatic hydrocarbons such as xylene, mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used, but at least 2.67 kPa (at 20 ° C. ) Having a high vapor pressure (toluene, ethyl acetate, propyl acetate, isopropyl acetate, methyl ethyl ketone, etc.) is more preferable. Among these, isopropyl acetate is particularly preferable. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  After application, the solvent may be removed in a drying process. In the drying process, a drying furnace can be used. In the drying furnace, it is possible to change the temperature condition, change the wind speed, etc. by appropriately setting several zones according to the material of the organic compound layer.

  Heat treatment may be performed after removing the solvent. The heat treatment is not limited to any form as long as heat is transferred from the back surface, but the heat treatment is preferably performed at a glass transition temperature of ± 50 ° C. and at a temperature not exceeding the decomposition temperature and heat transfer from the back surface. By performing the heat treatment, the smoothness of the film, the removal of the residual solvent, and the curing of the coating film can be achieved, thereby improving the element characteristics during lamination.

After the heat treatment, the substrate may be stored under reduced pressure (10 ⁻⁶ to 10 ⁻² Pa). You may apply temperature suitably. The storage period is preferably 1 to 200 hours, the longer the better. As a result, oxygen and trace moisture due to device deterioration are removed.

  After these layers are formed, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 V to 40 V with the anode as + and the cathode as-. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

《Wet process》
In the present invention, as an effective method for forming a very thin and highly smooth single layer coating film required for the organic layer of the organic electroluminescence device, a slot type coater coating method or an inkjet coating method is used. Is preferred. The slot type coater coating method or the ink jet coating method will be described in detail below.

  When a slot type coating coater is used, the uniformity of coating is further improved by installing a decompression chamber upstream of the coater and maintaining the bead portion in a decompressed state. This is because, by reducing the pressure at the lower part of the bead, even if the surface property and wettability of the support are changed, the liquid contact position of the coating liquid hardly fluctuates and a coating film having a uniform film thickness can be obtained.

  With the slot type coater coating method, the coating solution supplied from the coating solution supply device spreads across the coater die pocket, flows out from the slit at a uniform flow rate, and is spread evenly on the support. It is applied with a uniform coating thickness. As described above, it is a more preferable embodiment to install a decompression chamber device upstream of the coater die.

  The ink jet head is not particularly limited. For example, it may be a thermal type head that has a heating element and discharges the coating liquid from the nozzle by a rapid volume change due to film boiling of the coating liquid by the heat energy from the heating element. A shear mode type (piezo type) head that has a vibration plate including a piezoelectric element in the ink pressure chamber and discharges the coating liquid by a pressure change of the ink pressure chamber by the vibration plate may be used.

  FIG. 1 is a schematic diagram showing an example of a coating apparatus applied to the method for producing an organic EL element of the present invention. FIG. 1 shows an example in which three types of coating solutions are applied in layers to form a three-layer coating film. A two-layer coating is performed using a slot coater (hereinafter also abbreviated as a coater), and one layer is an inkjet. It is an example. FIG. 2 is an enlarged side view of the coating apparatus shown in FIG. 1 viewed from the direction of arrow Z1. The coaters 11 and 21 are sectional views.

  The long support 1 wound in the form of a roll is unwound in the direction of arrow B from the unwinding roll (not shown) by a driving means (not shown) and conveyed.

  An elongate support 1 is conveyed while being supported by a backup roll 2, and an inkjet head disposed in a coater 11 of a coating unit 10, a coater 21 of a coating unit 20, and an inkjet unit 31 of a coating unit 30 as coating means. By 311, the coating liquid is sequentially applied one layer at a time to form a three-layer multilayer coating film. The formed multilayer coating film is dried in a drying section (not shown) and wound on a winding roll (not shown).

  The coating unit 10 includes a coater 11, a liquid feed pump 12, a coating liquid tank 13, and a coating liquid supply pipe 14. The liquid feed pump 12 supplies the coating liquid stored in the coating liquid tank 13 to the coater 11 via the coating liquid supply pipe 14. The coater 11 has a slit 111 corresponding to the coating width in the support width direction, and is disposed at a position facing the backup roll 2 with the support 1 interposed therebetween. The coater 11 performs coating by discharging a coating solution from the slit 111 onto the support 1. The coating unit 10 also has a function of uniformly discharging the coating liquid from the slit 111 across the width direction of the support 1.

  The coating unit 20 includes a coater 21, a liquid feed pump 22, a coating liquid tank 23, and a coating liquid supply pipe 24. The function is the same as that of the coating unit 10.

  The coating unit 30 includes an inkjet unit 31, an inkjet head 311 disposed in the inkjet unit 31, a coating solution tank 33, and a coating solution supply pipe 34. The inkjet head 311 is disposed at a position facing the backup roll 2 with the support 1 interposed therebetween. The coating liquid stored in the coating liquid tank 33 is supplied to the inkjet head 311 through the coating liquid supply pipe 34 and is ejected from the nozzles of the inkjet head 311 to the support 1. As a result, the coating liquid is applied to the support 1. The coating liquid is ejected from the nozzles of the ink jet head 311 toward the rotation center of the backup roll 2.

  An arbitrary number and arrangement of inkjet heads 311 are installed in the inkjet unit 31. The number and arrangement are appropriately set according to the coating liquid to be used and the coating conditions, such as the ejection width of the inkjet head 311 and the coating width of the support 1.

  The coating unit 30 supplies a coating liquid to the inkjet head 311 and also has a function of keeping the coating liquid pressure in the inkjet head 311 constant.

  The inkjet head 311 is not particularly limited. For example, a thermal type head that has a heating element and discharges the coating liquid from the nozzle by a rapid volume change due to film boiling of the coating liquid by the heat energy from the heating element may be used. A shear mode type (piezo type) head that has a vibration plate including a piezoelectric element in the ink pressure chamber and discharges the coating liquid by a pressure change of the ink pressure chamber by the vibration plate may be used.

  FIG. 3 is a schematic plan view showing an example of an installation arrangement of the inkjet heads 311 used in the coating apparatus shown in FIG.

  In FIG. 3, reference numerals 311-1 to 311-5 denote ink jet heads arranged. Ink-jet heads 311-1 to 311-5 are arranged such that the surfaces of the heads 311-1 to 311-5 having the nozzle discharge ports and the coating film surface of the support 1 are parallel to each other and maintain a constant interval. The angle formed by the line connecting the centers of the nozzle outlets arranged in the width direction orthogonal to the direction and the moving direction of the support 1 is 90 °.

  Moreover, in order to eliminate an uncoated part between adjacent heads, the ends of the heads 311-1 to 311-5 are arranged in a staggered manner so as to overlap each other. By using a plurality of heads as described above and arranging them as shown in this figure, it becomes easy to cope with the width of the support 1, and there is no uncoated portion between the heads, and a stable coating film can be obtained. .

  The coaters 11 and 21 and the ink jet head 311 are arranged along the circumference of the backup roll 2 at a predetermined interval.

  The coating solution of the organic EL material used for the organic EL layer has a property of being easily dried. For this reason, depending on the progress of the drying of the first coating liquid applied by the coater 11, even if the second coating liquid is applied by the coater 21, the mixing does not occur.

  Therefore, when coating is performed at a predetermined interval, the coating film can be laminated without causing mixing of the coating solution. Here, the time during which the coating liquids do not mix with each other can be measured and set in advance for each coating liquid by an experiment or the like. The predetermined interval can be set from the time during which the measured coating solutions do not mix with each other and the moving speed of the support 1.

  Further, the diameter of the backup roll 2 can be set from the predetermined interval and the number of coating units to be arranged.

  Here, the diameter of the backup roll is preferably in the range of 0.5 to 5 m. If the length is less than 0.5 m, the number of coating units to be disposed is small, and the number of layers that can be coated in one pass is small, resulting in a reduction in production efficiency. Further, when the number of layers that can be applied in one pass is reduced, the number of windings increases, and the coating film surface is easily damaged during the winding. If it exceeds 5 m, the production of the backup roll 2 becomes difficult and the maintainability is also reduced.

  Moreover, the coating film thickness after drying of one coating layer is not particularly limited, but is usually about 5 nm to 5 μm, and more preferably 5 nm to 200 nm.

  The coating speed by this method is preferably 1 m / min to 10 m / min, more preferably 1 m / min to 5 m / min. Since the film thickness after coating and drying is thin, when the coating speed is 10 m / min or less, coating can be performed stably and quality defects can be suppressed.

  In addition, since the upper layer is applied after sufficiently drying, mixing between layers hardly occurs, and this also leads to prevention of quality defects.

  In this embodiment, a combination of a coater and an ink jet is used, such as two coaters and one ink jet. However, all coaters may be used, or all may be configured as an ink jet.

<< Display device, lighting device >>
A display device and an illumination device to which the organic EL element according to the present invention is applied will be described. The organic EL element according to the present invention may be used as a projection device for projecting an image, a display device (display) for directly viewing a still image or a moving image, or as an illumination or exposure light source. It may be used as a kind of lamp.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless there is particular notice, it represents "mass part" or "mass%". Moreover, the structure of the compound used in an Example is shown below.

Example 1
<< Production of Organic EL Element 101 >>
A transparent gas barrier film was prepared on a polyethersulfone (Sumitomo Bakelite film, hereinafter abbreviated as PES) having a thickness of 200 μm as an anode using an atmospheric pressure plasma polymerization method.

  Subsequently, 120 nm of ITO (indium tin oxide) was formed on this gas barrier film substrate. The roll-shaped strip-shaped flexible sheet on which the anode was formed was fed out and wound into a roll through a cleaning surface modification treatment step and a charge removal treatment step.

As the cleaning surface modification treatment, the dry washing surface modification treatment apparatus was carried out at a low pressure mercury lamp wavelength of 184.9 nm, an irradiation intensity of 15 mW / cm ² , and an irradiation distance of 10 mm.

  As the charge removal treatment, a static eliminator using weak X-rays was used.

  On this substrate, a poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) diluted to 70% with pure water was used as a backup roll having a diameter of 3 m. Then, after forming a film at a coating speed of 4 m / min by the slot type coater method, the film was dried at 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 30 nm.

  A coating solution for the hole transport layer is prepared as follows, using a backup roll having a diameter of 3 m, using a slot type coater, a coating speed of 4 m / min, and the film thickness after drying becomes a hole transport layer of 20 nm. It was applied as follows.

This substrate was heated at 150 ° C. for 10 seconds, and irradiated with 30 mW / cm ² of ultraviolet light for 20 seconds using a high pressure mercury lamp (OHD-110M-ST, manufactured by Oak Manufacturing Co., Ltd.). Furthermore, it heated at 120 degreeC for 30 minute (s), and provided the positive hole transport layer.

(Coating liquid for hole transport layer)
A coating solution for a hole transport layer was prepared by dissolving HT-A in toluene at 0.45 mass% and HT-B at 0.05 mass%.

  Next, a light emitting layer coating solution was prepared as follows, and a coating roll of 4 m / min and a film thickness after drying of 50 nm were applied using a slot type coater using a backup roll having a diameter of 3 m. .

(Light emitting layer coating solution)
A luminescent layer coating solution was prepared by dissolving 1% by mass of H-31 and 0.1% by mass of perylene in butyl acetate.

  Immediately after the application of the light emitting layer, the solvent was removed by a drying treatment step using a heated air stream. It was carried out at a height of 100 mm from the slit nozzle type ejection port toward the film formation surface, an ejection wind speed of 1 m / second, a width distribution of 5%, and a drying temperature of 100 ° C.

  The film thickness of the light emitting layer was measured with a spectroscopic ellipsometer from the application to the removal of the solvent in the drying treatment step using a heated air stream. The time taken to dry to 52.5 nm, which is 5% increase in film thickness after drying from the start of coating, was 28 seconds.

  Separately, a light emitting layer was provided on the prepared substrate in the same manner as described above. The crystallinity is calculated by X-ray diffraction measurement at five points near the center of the substrate, and the average of the five points is 5%. It was done.

  Next, a coating solution for the electron transport layer was prepared as follows, and a coating roll was applied at a coating speed of 4 m / min and a film thickness after drying of 30 nm using a backup roll having a diameter of 3 m and a slot type coater. did.

(Coating liquid for electron transport layer)
In 2,2,3,3-tetrafluoro-1-propanol, ET-A was dissolved at 0.75 mass% to prepare a coating solution for an electron transport layer.

  After coating, the solvent was removed in a drying process using a heated air stream. It was carried out at a height of 100 mm from the slit nozzle type ejection port toward the film formation surface, an ejection wind speed of 1 m / second, a width distribution of 5%, and a drying temperature of 100 ° C.

  After removing the solvent, the substrate was sucked and transported by sucking heat rolls having a temperature of 150 ° C. from closely arranged rolls, and heat treatment was performed by heating by back surface heat transfer.

The wound roll was stored in a storage box and stored under reduced pressure (10 ⁻⁶ to 10 ⁻² Pa). The obtained roll-shaped film was moved to a vapor deposition machine, and the substrate provided up to the electron transport layer was depressurized to 4 × 10 ⁻⁴ Pa. Note that cesium fluoride and aluminum were each placed in a tantalum resistance heating boat and attached to a vapor deposition machine.

  Using an evaporation head on the electron transport layer, cesium fluoride having a thickness of 3 nm was evaporated as an electron injection layer.

  Subsequently, an aluminum layer having a thickness of 100 nm was also vapor-deposited in a region including the organic EL layer region and the electrode extraction region, and a cathode was provided.

  A substrate provided up to the cathode is formed by winding an inorganic film such as SiOx, SiNx or a composite film as a 300 nm sealing film using a sputtering method, a plasma CVD method, an ion plating method, etc. in a region other than an electrode region, An EL element 101 was obtained.

<< Production of Organic EL Element 102 >>
In the production of the organic EL element 101, the organic EL element 102 was produced in the same manner except that the coating and drying conditions of the light emitting layer were changed as follows.

  After forming up to the hole transport layer of the organic EL device 102 in the same manner as the organic EL device 101, a coating solution for the light emitting layer is prepared as follows, a backup roll having a diameter of 3 m is used, and a slot type coater is used. Then, coating was performed so that the coating speed was 4 m / min and the film thickness after drying was 50 nm.

(Light emitting layer coating solution)
A luminescent layer coating solution was prepared by dissolving 1% by mass of H-31 and 0.1% by mass of perylene in butyl acetate.

  Immediately after the application of the light emitting layer, the solvent was removed by a drying treatment step using a heated air stream. It was carried out at a height of 100 mm from the slit nozzle type ejection port toward the film formation surface, an ejection wind speed of 1.5 m / sec, a width distribution of 5%, and a drying temperature of 100 ° C.

  The film thickness of the light emitting layer was measured with a spectroscopic ellipsometer from the application to the removal of the solvent in the drying treatment step using a heated air stream. It took 18 seconds to dry from the start of coating to 52.5 nm, which is a 5% increase in the film thickness after drying.

  Separately, a light emitting layer was provided on the prepared substrate in the same manner as described above. The crystallinity was calculated by X-ray diffraction measurement at five points near the center of the substrate, and the average of the five points was 0.5%. In the light emitting layer, X-ray diffraction peaks due to microcrystals were obtained. Was not detected.

<< Production of Organic EL Elements 103-110 >>
In the production of the organic EL element 101, organic EL elements 103 to 110 were produced in the same manner except that the host, the dopant, the coating solvent for the light emitting layer, and the drying conditions were changed as shown in Table 1.

<< Production of Organic EL Element 201 >>
In the production of the organic EL element 101 by the slot coater coating method, an organic EL element 201 was produced in the same manner except that a hole transport layer, a light emitting layer, and an electron transport layer were provided by the following procedure.

(Preparation of hole transport layer, light emitting layer, and electron transport layer in organic EL element 201)
A coating solution for the hole transport layer was prepared in the same manner as the solution used in the production of the organic EL element 101, and after using a 3 m diameter backup roll and an inkjet coating apparatus, a coating speed of 4 m / min, after drying. The film thickness was applied so that the hole transport layer was 20 nm.

This substrate was heated at 150 ° C. for 10 seconds, and irradiated with 30 mW / cm ² of ultraviolet light for 20 seconds using a high pressure mercury lamp (OHD-110M-ST, manufactured by Oak Manufacturing Co., Ltd.). Furthermore, it heated at 120 degreeC for 30 minute (s), and provided the positive hole transport layer.

  Next, a coating solution for the light emitting layer was prepared in the same manner as the solution used in the production of the organic EL element 101, and after using a 3 m diameter backup roll and an inkjet coating apparatus, a coating speed of 4 m / min, after drying. Two liquids were applied so that the film thickness was 50 nm.

  Immediately after the application of the light emitting layer, the solvent was removed by a drying treatment step using a heated air stream. It was carried out at a height of 100 mm from the slit nozzle type ejection port toward the film formation surface, an ejection wind speed of 1.5 m / sec, a width distribution of 5%, and a drying temperature of 100 ° C. The film thickness of the light emitting layer was measured with a spectroscopic ellipsometer from the application to the removal of the solvent in the drying treatment step using a heated air stream.

  The time taken to dry to 52.5 nm, which is a 5% increase in film thickness after drying from the start of coating, was 20 seconds.

  Separately, a light emitting layer was provided on the prepared substrate in the same manner as described above. The crystallinity was calculated by X-ray diffraction measurement at five points near the center of the substrate, and the average of the five points was 0.7%. In the light emitting layer, the X-ray diffraction peak due to microcrystals was Not detected.

  Next, an electron transport layer coating solution was prepared in the same manner as the solution used in the production of the organic EL element 101, a 3 m diameter backup roll was used, an ink jet coating apparatus was used, and a coating speed was 4 m / min. It applied so that the film thickness after drying of a layer might be set to 30 nm.

<< Evaluation of organic electroluminescence element >>
About the produced organic electroluminescent element (the organic EL elements 101-110, the organic EL element 201), the power efficiency and the light emission lifetime were evaluated as follows.

《Power efficiency》
The power efficiency (lm / W) when a ^2.5 mA / cm ² constant current was applied to the produced organic electroluminescence element was measured. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used. The power efficiency of the organic electroluminescence elements (organic EL elements 101 to 110, organic EL element 201) was expressed as a relative value with the measured value of the organic EL element 101 as 100.

<Luminescent life>
The produced organic electroluminescence element was continuously driven by applying a current having a front luminance of 1000 cd / m ² . The time required for the front luminance to reach the initial half value (500 cd / m ² ) is obtained, and the lifetime of the organic electroluminescence elements (organic EL elements 101 to 110, organic EL element 201) is measured by the measured value of the organic EL element 101. Expressed as a relative value of 100.

(Calculation of molecular weight of host compound)
In the calculation of the molecular weight of the host compound shown in Table 1 below, the following atomic weight values were used. For polyvinyl carbazole, which is a polymer, a measured value (number average molecular weight) by a conventionally known GPC method was used.

C (carbon atom) = 12.011
H (hydrogen atom) = 1.00794
N (nitrogen atom) = 14.600674
O (oxygen atom) = 15.9994
In the calculation of molecular weight, the above-mentioned atomic weight value was used, and the value obtained by rounding off the last four digits was used.

_{H-18 (C 51 H 33} N 5) = 715.857
_{H-27 (C 42 H 26} N 2 O) = 574.681
_{H-31 (C 102 H 64} N 6) = 1373.671
The obtained results are shown in Table 1.

  From Table 1, compared with the comparative organic EL element 101 in which microcrystals are detected, the organic EL element of the present invention in which microcrystals are not detected by X-ray diffraction in the light emitting layer has high power efficiency, and It is clear that the light emission lifetime is also increased.

  Furthermore, it turned out that the organic EL element of this invention which raised both power efficiency and the light emission lifetime can be usefully used as both the display apparatus of this invention, and an illuminating device.

DESCRIPTION OF SYMBOLS 1 Support body 2 Backup roll 10, 20, 30 Coating unit 11, 12 Coater 12, 22 Liquid feed pump 13, 23, 33 Coating liquid tank 111, 211 Slit 31 Inkjet unit 311 Inkjet head

Claims (8)

Anode, as a layer between a cathode, and at least one layer producing method of an organic electroluminescence element having a luminescent layer of which contains a dopant and a host, the light emitting layer is deposited by a coating method, at least a light emitting layer One layer is a light emitting layer made of a low molecular organic compound, and the light emitting layer has a drying time of 20 seconds or less until the film thickness increases by 5% of the final film thickness after coating, film formation and drying of the light emitting layer. and a step of forming a and method of producing an organic electroluminescent device X-ray diffraction peak due to crystallites of the low-molecular organic compound of the light emitting layer is equal to or not detected. The method for producing an organic electroluminescence device according to claim 1, wherein the host has a molecular weight of 1500 or less. The method for producing an organic electroluminescence element according to claim 1, wherein the host has a molecular weight of 800 or less. The method for producing an organic electroluminescent element according to claim 1, wherein the host has at least three partial structures represented by the following general formula (a) in one molecule. .

[Wherein X represents NR ′, O, S, CR′R ″ or SiR′R ″. R ′ and R ″ each represent a hydrogen atom or a substituent. Ar represents an atomic group necessary for forming an aromatic ring. N represents an integer of 0 to 8.] Method of manufacturing an organic electroluminescent device according to any one of claims 1-4 wherein said dopant is characterized in that exhibits phosphorescence. The said dopant is represented by following General formula (1), The manufacturing method of the organic electroluminescent element of Claim 5 characterized by the above-mentioned.

[Wherein, Z represents a hydrocarbon ring group, an aromatic heterocyclic group or a heterocyclic group. R _{81 to} R ₈₆ each represent a hydrogen atom or a substituent. P ₁ -L ₁ -P ₂ represents a bidentate ligand, and P ₁ and P ₂ each independently represent a carbon atom, a nitrogen atom or an oxygen atom. L1 represents an atomic group forming a bidentate ligand together with P ₁ and P ₂ . j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, and j1 + j2 is 2 or 3. M ₁ represents a group 8-10 metal element in the periodic table. ] The method for producing an organic electroluminescent element according to claim 6, wherein M _{1 in the} general formula (1) is iridium. The method for producing an organic electroluminescence element according to claim 1, wherein the drying time is 10 seconds or less .

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