KR100788152B1 - Production method and device for organic EL element - Google Patents

Abstract

The present invention relates to a method for producing an organic EL device having good device performance by preventing the deterioration of the organic EL material when the organic EL material is deposited on a substrate, and an apparatus used therefor. In the organic EL device deposition method of the present invention, in the organic EL thin film deposition in which an organic EL material in an evaporation source is vaporized and deposited on the film forming substrate 4, a thin film is formed. It is a method of using the organic EL element vapor deposition apparatus which made the material of components, such as the chamber or shutters 5 and 6 which the said organic material precipitates other than a film-forming board | substrate, into an inert material which does not deteriorate the said organic material. .

Description

Production method and device for organic EL element

The present invention relates to a method and apparatus for producing an organic EL device by vaporizing an organic EL device material (also referred to as an organic EL material) in order to prepare an organic thin film for an organic EL device by a vacuum deposition method.

As a general structure of the organic EL element, an organic thin film layer such as a hole transporting layer, a light emitting layer, an electron transporting layer is formed between an anode and a cathode made of a transparent conductive film, and holes injected from the cathode to the light emitting layer through the hole transporting layer; Light emission occurs when electrons injected into the light emitting layer from the cathode through the electron transport layer recombine. At this time, depending on impurities and altered substances in the material, so-called dark spots are generated by co-deposition, and problems such as appearance of uncolored color appear when the display device is used. .

It is known from Japanese Patent Laid-Open No. 2000-68055 or the like that there is a vacuum evaporation method as one of methods for preparing an organic thin film for an organic EL device. In the vacuum vapor deposition method, the vapor deposition material vaporized from the evaporation source heated above the vaporization temperature of the vapor deposition material which is an organic EL material deposits as a solid on the film-forming board | substrate, and forms a thin film.                 

At this time, it is important to make the film thickness uniform, but generally, a method of stabilizing the amount of evaporation from the evaporation source and then depositing on the substrate surface is taken. For that purpose, shutters are provided at one or both sides of the evaporation source and the substrate near the evaporation apparatus, and the evaporation rate is stabilized while the evaporation rate is stabilized while monitoring the evaporation rate of the organic EL material vaporized from the evaporation source. An operation to start vapor deposition is performed. Since the shutter covers the evaporation source and the substrate again at the timing of changing the substrate, changing the organic EL material to be deposited, or the like, there is a possibility that the material deposited on the shutter facing the evaporation source may fall on the evaporation source due to the shock caused by the opening and closing.

As a method of making film thickness uniform, the method of taking a long distance between an evaporation source and a board | substrate is generally used together. In general, a vacuum evaporation apparatus for organic EL elements uses a vessel such as a boat or a crucible as an evaporation source, and gaseous molecules of an organic EL material vaporized from the evaporation source rise and widen so as to exhibit an inverted triangular pyramid with the evaporation source as a vertex. Reach and deposit on the substrate. In any cross section of the inverted triangular pyramid, the concentration of gaseous molecules at the center is the highest, and the concentration decreases as the radial distance increases. The radial concentration change of this gaseous molecule is larger as it is closer to the evaporation source and closer to the center of the inverted triangular pyramid, and becomes smaller as they are farther.

Therefore, in the film thickness distribution on the substrate, the thickness of the portion where the center portion of the inverted triangular pyramidal gas-shaped molecules is deposited is thick, and the thickness of the portion where the peripheral portion is deposited is thin. Therefore, by lengthening the distance between the evaporation source and the substrate, the gaseous molecular concentration on the substrate surface is averaged as much as possible, or only the periphery of the inverted triangular gaseous molecular phase is deposited on the substrate surface. In many cases, the film thickness can be uniformized. However, in the former case, the diffusion of gaseous molecules is increased, and a considerable amount is deposited in the device inner wall surface and the like other than the substrate surface. In the latter case, there is an advantage that the device is small, but gaseous molecules in the center portion of the inverted triangular pyramid, which is the highest concentration, do not precipitate on the substrate surface. The problem is bigger.

The organic EL material deposited in this manner other than the substrate surface may fall on the evaporation source and co-deposit if it is deposited. Therefore, the material deposited on parts such as the device inner wall surface and the shutter that may fall on the evaporation source may not be deteriorated. It is important.

In general, organic EL materials to be deposited are expensive organic compounds, and therefore, it is expected to recover them and use them. Therefore, in order to recover and reclaim the material deposited on the inner wall surface of the device other than the substrate, it is important not to deteriorate the organic EL material.

Generally, in the vacuum evaporation apparatus for organic electroluminescent element, the material of the part in which the gaseous molecule | numerator of organic electroluminescent material precipitates, for example, the vacuum chamber main body, the shutter installed in a chamber, or what is called an anti-stick plate is used. Austenitic stainless steels (sometimes abbreviated as SUS) are often used for materials of parts such as the included accessories, which are inexpensive, have good workability, and are excellent in rust resistance. However, depending on the organic EL material to be used, part of the precipitate is deteriorated or contaminated.

For example, in an organometallic complex compound such as 8-hydroxyquinoline aluminum (may be abbreviated as Alq3) known as a representative organic EL material, iron in the SUS plate and aluminum in the organometallic complex The metal exchange reaction may occur to produce an 8-oxyquinoline iron complex. This 8-oxyquinoline iron complex is also vaporized. In addition, when the organic EL material is corrosive or forms an oxidizing atmosphere, iron rust or the like is generated. It is an organic EL material that does not contain a metal element, and even when it is not corrosive, the temperature change is repeatedly generated due to the operation and rest of the apparatus. As a result, the firmly adhered organic EL material and the SUS metal plate Due to the difference in thermal expansion rate, abrasion occurs on the SUS surface or cyclic stress occurs on the bonding surface of the SUS metal and the organic EL material, and very small uneven surface texture on the surface of the SUS metal plate causes metal fatigue, resulting in organic EL material When the flakes are peeled off from the metal surface, the phenomenon of mechanically peeling together the surface tissue of the tiny convex portions of the metal surface may occur.

When the deteriorated organic EL material falls on the evaporation source, vaporizes, and co-deposits on the substrate, device performance deteriorates. In addition, if there is a quality substance in the recovered organic EL material, the regenerated material is contaminated with impurities, and the performance of the device created by using the same decreases or it becomes difficult to purify the regenerated use.

Accordingly, it is an object of the present invention to provide a method for producing an organic EL element and a device for use in which it is possible to prevent deterioration or contamination of an organic EL material and to produce a good quality organic EL element with good yield.                 

The manufacturing method of the organic electroluminescent element of this invention is an apparatus in which the said organic material other than a substrate surface deposits in the organic electroluminescent thin film deposition which vaporizes the organic material for organic electroluminescent elements, and deposits on a film-forming board | substrate to form a thin film. It is a method of carrying out organic electroluminescent thin film deposition using the material provided in an inner wall surface and the inside of an apparatus as an inert material with respect to the said organic material. Here, it is advantageous to recover and reuse the organic material deposited other than the substrate surface.

The organic EL thin film deposition apparatus of the present invention is an organic EL thin film deposition in which an organic material for an organic EL element is vaporized and deposited on a film formation substrate to form a thin film. It is an apparatus in which the wall surface and the components installed inside the apparatus are made of a material which is inert to the organic material. Here, as said component, a shutter is illustrated preferably. Moreover, it is also preferable to set at least the surface layer surface of the said device inner wall surface and the component provided in the inside of the apparatus to an inert material with respect to the vaporizing organic material.

1 is a cross-sectional view showing an example of the organic EL element deposition apparatus of the present invention, which is composed of a chamber 1, an evaporation source 2, an organic EL material 3, a substrate 4, and shutters 5 and 6; have.

EMBODIMENT OF THE INVENTION Hereinafter, the organic EL thin film vapor deposition apparatus of this invention and the vapor deposition method using the same are demonstrated in detail. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows an example of the apparatus of this invention.                 

The vacuum vapor deposition apparatus includes a chamber 1 capable of vacuuming, an evaporation source 2 such as a crucible disposed in the chamber 1, holding means for holding the substrate 4 at a predetermined position (not shown), The shutters 5 and 6 which substantially control the timing for depositing are provided as components. In this figure, the shutter 5 is formed near the evaporation source, and the shutter 6 is formed near the substrate, but may be formed only on either side.

The chamber 1 is capable of depressurizing with a vacuum pump or the like, and has a structure in which the organic EL material and the substrate that are charged inside can be put in and taken out. Then, the evaporation source 2 is heated, the inside of the chamber 1 is reduced in pressure, and the organic EL material 3 charged in the evaporation source is vaporized (evaporated or sublimed) at a constant speed as much as possible, and a monitoring device (not shown) To the substrate 4 by monitoring or controlling the vaporization speed, and opening the shutters 5 and 6 if the vaporization speed is constant or controlling the opening degree of the shutters 5 and 6 according to the vaporization speed. The adhesion rate or amount or thickness of the organic EL material is controlled.

In the vacuum vapor deposition apparatus in this example, although the container shape of an evaporation source is made into the crucible shape, it is not limited to this. In addition, although only one evaporation source 2 is described, it is also possible to exist in multiple numbers. On the other hand, as the parts disposed in the chamber 1 and located at the position to which the organic EL material adheres, only the shutters 5 and 6 are shown for simplifying the drawing and facilitating the understanding. Many parts are installed. For example, there may be a case where a protective plate that can be attached and detached is provided mainly for the purpose of reducing the cleaning work of the material deposited on the chamber inner wall. This anti-glare plate is bent in a thin SUS plate, is installed in the chamber along the inner wall of the chamber, and is often divided and installed to facilitate attachment and detachment.

In the case where the organic EL material is a material for forming the light emitting layer, an organometallic complex is often used. When the complex metal is in contact with a dissimilar metal under high temperature, metal exchange, that is, alteration occurs at a predetermined ratio. Therefore, if the materials other than the substrate on which the organometallic complex precipitates are not inert to the organometallic complex, the organometallic complex is deteriorated.

In addition to the substrate, examples of the site where the organometallic complex precipitates include the inner wall of the chamber 1, the shutters 5 and 6 facing the evaporation source, and so-called anti-glare plates.

The components such as the chamber 1 and the shutters 5 and 6 may be made of a material such as one kind of metal material, or may be made of two or more layers of materials, and at least the surface layer portion on which the vaporized organic EL material is deposited. The material of is preferably made of a material which is inert to the organic EL material. In addition, instead of making the material of the chamber 1 into an inert material, what is called a protection board may be made into an inert material.

The inert material referred to in the present invention means that in contact with the organic EL material, not only the material itself but also the organic EL material are not deteriorated, decomposed or contaminated by corrosion of the material. Although specifically, it refers to what arises because a material, such as the chamber 1, and organic electroluminescent material contact, the material corrodes and changes in quality due to the atmosphere. However, it is not meant to include the case where the organic EL material is merely pyrolyzed, but it is limited to promoting it and causing corrosion, deterioration and contamination in a realistic manner in the atmosphere.                 

Preferred materials for use in the present invention include precious metals such as gold, heat resistant resins such as fluorine resins, polyimide resins and silicone resins, glass such as quartz glass, pyrex, hard glass, enamel, Nonmetallic materials, such as ceramics, such as an alumina, a silicon nitride, and a porcelain, etc. are mentioned. Among these, considering processability, cost, etc., it can select suitably. Preferable inert materials include metals, glass such as enamel, fluororesins and ceramics. Among these, it is advantageous that the material having no strength, or difficult to be molded, or an expensive material be made of only an inert surface layer portion by means such as thin film deposition or plating.

In addition, in the case of the organometallic complex EL material, in addition to the inert material, a material having, on the surface, a noble metal which does not cause a metal exchange reaction with the metal or at least the same metal material as the metal can be employed. For example, in the case of Alq3, the material which coated aluminum on the surface besides an aluminum material can be used.

Next, the deposition method using the apparatus of the present invention will be described.

The evaporation source 2 is charged with a predetermined amount of the organic EL material 3 to be deposited. Moreover, the surface which the board | substrate 4 which may have already formed several layers by vapor deposition etc. deposits is set toward the evaporation source 2 side. It is advantageous to arrange the substrate 4 directly above the evaporation source 2 in terms of deposition rate. There is a risk that the adherent deposits fall into the evaporation source 2 when the shutter is opened or closed or the substrate is replaced. In the case of using the vapor deposition apparatus of the present invention, there is no deterioration or contamination of the deposit even in such a case, thereby solving the problem thereby.                 

Thereafter, pressure reduction and heating are performed, and vaporization is started. The temperature of the evaporation source 2 and the surrounding evaporation section may be any temperature at which a predetermined vapor pressure of the organic EL material 3 can be obtained. Usually, this vapor pressure is about 10 ^-8 Torr from several Torr. Since the vaporization rate is not stabilized immediately after the start of vaporization, the shutter covers the evaporation source or the substrate. The vaporization rate is monitored by a film thickness sensor or the like, and when the vaporization rate is stabilized, the evaporation source or the shutters 5 and 6 covering the substrate are opened to start vapor deposition on the substrate. Other deposition conditions may employ a known method, and the present invention is not limited to the apparatus and operating conditions described in the drawings or the examples below. In addition, an organic EL material is not limited to metal complexes, such as Alq3, and is applicable to all the organic EL materials used for manufacture of an organic EL element.

<Example>

Hereinafter, the specific example of this invention is described based on an Example.

(Comparative Example 1)

High purity 8-hydroxyquinoline aluminum (Alq3) was vapor-deposited on the board | substrate using the vapor deposition apparatus shown in FIG. The material of the shutters 5 and 6 was made of SUS304.

After the deposition was completed, Alq3 deposited on the shutter 5 facing the evaporation source near the evaporation source was recovered and analyzed to find iron and chromium. This was presumed to be a metal exchanged complex with Alq3.

Next, the said collection Alq3 is collected and made into a light emitting layer and an electron carrying layer, and N, N'-di- (naphthalene-1) is carried out on the ITO transparent electrode of the glass substrate in which the ITO film | membrane is already formed using the same apparatus as the above. -Il) -N, N'-diphenyl-benzidine (henceforth NPB) is used as a hole transport layer, and the laminated element which has the said Alq3 and the aluminum-lithium cathode subsequently was created. On the other hand, the thickness of all the organic materials was 50 nm, and the electrode was 200 nm for both ITO and aluminum-lithium. As a result of observing the device with a fluorescence microscope immediately after encapsulation, several dark spots per 1000 µm x 1000 µm were observed.

(Example 1)

Molten aluminum plating was performed to the shutter, and Alq3 was deposited on the conditions similar to the comparative example 1 except that. The complex which caused metal exchange was not detected in Alq3 deposited on the shutter 5 which faced the evaporation source near the evaporation source after completion | finish of vapor deposition.

This deposit was collected, and the same laminated element as described in Comparative Example 1 was prepared under the same conditions as in Comparative Example 1, which was used as the light emitting layer and the electron transporting layer, and the NPB was the hole transporting layer. As a result of observing the device with a fluorescence microscope immediately after encapsulation, the number of dark spots was greatly reduced.

According to the present invention, the organic EL device performance is improved by preventing the deterioration of the organic EL material that is deposited on the site that can be mixed into the evaporation source due to mechanical shock or the like. In addition, it is easy to regenerate and use unused organic EL materials.

Claims (6)

delete An organic EL device manufacturing method using an apparatus for depositing an organic EL thin film comprising a chamber, an evaporation source disposed in the chamber, and at least one shutter disposed in the chamber, Charging an organic material made of an organometallic complex for an organic EL device into the evaporation source; Vaporizing the organic material through reduced pressure and heating; Opening the shutter and depositing the film on the film forming substrate; And And recovering and reusing the organic material deposited in addition to the film forming substrate. In addition to the film forming substrate, an inner wall surface of the chamber in which the organic material is deposited and a component disposed in the chamber are made of a material which is inert to the organic material. An organic EL thin film vapor deposition apparatus which vaporizes an organic material which consists of an organometallic complex for organic EL elements, and deposits on a film-forming board | substrate to form a thin film, Comprising: chamber; An evaporation source disposed in the chamber; A holding means disposed in the chamber, for holding the film forming substrate at a predetermined position; At least one shutter disposed in the chamber and positioned between the evaporation source and the holding means; And an inner wall surface of the chamber in which the organic material is deposited, and a component disposed inside the chamber, in addition to the film forming substrate, a material inert to the organic material. The method of claim 3, Inorganic EL thin film deposition apparatus, characterized in that the material inert to the organic material is metals, glass, fluorine resin or ceramics. The method of claim 3, The organic material is an 8-hydroxyquinoline aluminum complex, And an inert material for the organic material is aluminum. The method of claim 3, It is installed along the inner wall of the chamber, and further includes a removable anti-stick plate, And the anti-corrosion plate is made of a material which is inert to the organic material.

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