JP2009266719A - Manufacturing method of organic electroluminescent element, and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic electroluminescent element capable of forming an organic functional layer uniform in film thickness by using a coating method capable of forming a coating uniform in film thickness by reducing the distance from the coating start to a point with film thickness set constant; and an organic electroluminescent element manufactured by the manufacturing method. <P>SOLUTION: This manufacturing method of an organic EL element is used for manufacturing an organic EL element by laminating, on a substrate, at least a positive electrode, a negative electrode, and one or more organic functional layers located between the positive electrode and the negative electrode. The manufacturing method includes a process of bringing a nozzle arranged by directing a slit upward close to a substrate from the lower side in a state where a coating liquid containing a material becoming the organic functional layer(s) is pushed out from the nozzle, and forming coatings by relatively moving the nozzle and the substrate with the coating liquid adhered to the substrate side to form the organic functional layers, wherein the rise velocity of the nozzle is 0.7 m/min in bringing the nozzle close to the substrate from the lower side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an organic electroluminescent element and an organic electroluminescent element.

  As one of elements that emit light when voltage is applied, there is an organic EL (Electro Luminescence) element in which a light emitting portion is made of an organic substance. An organic EL element is usually formed by laminating an anode, a cathode, and one or more organic functional layers located between the anode and the cathode on a substrate. The organic EL element includes at least a light emitting layer as the organic functional layer, and by applying a voltage, holes are injected from the anode, electrons are injected from the cathode, and these holes and electrons are combined. Emits light.

  The organic functional layer is formed, for example, by forming a coating solution containing a material to be the organic functional layer by a coating method and further drying. One method for applying a coating solution is a capillary coating method using capillary action. In the capillary coating method, the coating liquid is attached to the substrate side by bringing the nozzle close to the substrate from below in a state where the coating liquid is extruded from a nozzle disposed with the slit facing upward, and the coating liquid is attached to the substrate side. The coating film is formed by relatively moving the nozzle and the substrate while adhering to the substrate (see, for example, Patent Document 1).

JP 2004-164873 A

  In the application using the capillary coating method, the film thickness becomes thicker than the initial film thickness at the beginning of application, and as the application proceeds further, it gradually approaches the desired film thickness, and finally reaches the desired film thickness. It is normal. In the conventionally used capillary coating method, there is a problem that the distance from the start of coating to the film thickness of the coating film becomes long. For example, when the above-described light emitting layer is formed by using such a capillary coating method, a difference in emission intensity occurs between a thick part and a uniform part, and a thick coating start part is a product. Since it may not be used, there is a need for a coating method that can shorten the distance from the beginning of coating until the film thickness of the coating film becomes constant.

  Therefore, the object of the present invention is to reduce the distance from the start of coating until the film thickness of the coating film becomes constant, and to use a coating method that can form a coating film with a uniform film thickness. It is providing the manufacturing method of the organic electroluminescent element which can form an organic functional layer, and the organic electroluminescent element manufactured by this manufacturing method.

The present invention is a method for producing an organic electroluminescence device by laminating at least an anode, a cathode, and one or a plurality of organic functional layers located between the anode and the cathode,
In a state where the coating liquid containing the material to be the organic functional layer is extruded from a nozzle arranged with the slit facing upward, the nozzle is brought close to the substrate from below, and the coating liquid is attached to the substrate side. Forming a coating film by relatively moving the nozzle and the substrate, and forming the organic functional layer,
An organic electroluminescence element manufacturing method characterized in that an ascending speed when the nozzle is brought close to the substrate from below is 0.7 m / min (min) or more.

  Further, the present invention is characterized in that after the nozzle is brought close to the substrate from below, the nozzle is lowered at a speed of 0.7 m / min or more before the nozzle and the substrate are relatively moved. It is a manufacturing method of an organic electroluminescent element.

  Moreover, this invention is a manufacturing method of the organic electroluminescent element characterized by the relative speed at the time of moving relatively the said nozzle and a board | substrate being 0.7 m / min or more.

The present invention is also the method for producing an organic electroluminescent element, characterized in that a distance between the nozzle and the substrate when the nozzle and the substrate are relatively moved is 200 μm or more.
Moreover, this invention is an organic electroluminescent element manufactured with the manufacturing method of the said organic electroluminescent element.

  According to the present invention, in the step of forming the organic functional layer, the distance from the start of coating until the film thickness of the coating film becomes constant can be shortened by setting the rising speed of the nozzle within a predetermined range. Thus, an organic functional layer having a uniform film thickness can be formed.

  In the method of manufacturing an organic EL element according to the present embodiment, an organic EL element is manufactured by laminating at least an anode, a cathode, and one or more organic functional layers located between the anode and the cathode on a substrate. In the method, a coating liquid containing a material to be the organic functional layer is extruded from a nozzle disposed with a slit facing upward, and the nozzle is brought close to the substrate from below, so that the coating liquid is on the substrate side. A step of forming a coating film by relatively moving the nozzle and the substrate while adhering to the substrate, and forming the organic functional layer, wherein the nozzle has a rising speed when approaching the substrate from below. It is 0.7 m / min.

  The organic EL element includes at least an anode, a cathode, and a light emitting layer as an organic functional layer positioned between the anode and the cathode. Between the anode and the cathode, not only one light emitting layer, but also a plurality of light emitting layers, and / or one or a plurality of organic functional layers different from the light emitting layer, and an inorganic layer may be provided. Hereinafter, a process of forming a light emitting layer using the coating method of the present embodiment will be described.

  FIG. 1 is a diagram schematically showing a cap coater system 1 used for forming a light emitting layer. In the case where the organic EL element has an element structure in which, for example, an anode, a light emitting layer, and a cathode are laminated in this order on the substrate, the light emitting layer is formed on the substrate on which the anode is formed. Hereinafter, in the present specification, “upward” and “downward” mean “upward in the vertical direction” and “downward in the vertical direction”, respectively.

  The cap coater system 1 mainly includes a surface plate 2, a nozzle 3, and a tank 4. The surface plate 2 holds a substrate provided on a lower surface in the vertical direction. An example of a method for holding the substrate is vacuum suction. The surface plate 2 reciprocates in the horizontal direction by displacement driving means such as an electric motor and a hydraulic machine (not shown). Hereinafter, the direction in which the surface plate 2 moves may be referred to as a coating direction X.

  The nozzle 3 is arranged with the slit facing upward. The nozzle 3 has an opening at the upper end extending in the width direction Y perpendicular to the vertical direction Z and the application direction Y, and is formed with a plate-like application liquid supply hole 5 connected to the opening. The coating liquid supply hole 5 extends downward from the opening. The opening of the nozzle 3 has, for example, a width in the coating direction X of about 296 mm and a width in the width direction Y of about 260 mm. The nozzle 3 is supported so as to be displaceable in the vertical direction Z, and is driven to be displaced in the vertical direction Z by displacement driving means such as an electric motor and a hydraulic machine.

  The tank 4 stores the coating liquid 7. The coating liquid 7 accommodated in the tank 4 is a coating liquid 7 applied to the substrate 8 and is a liquid containing a material that becomes a light emitting layer in the present embodiment. Specifically, it is a solution in which a light emitting material described later is dissolved in a solvent. The coating liquid supply hole 5 of the nozzle 3 and the tank 4 communicate with each other through a coating liquid supply pipe 6. That is, the coating liquid 7 accommodated in the tank 4 is supplied to the coating liquid supply hole 5 through the coating liquid supply pipe 6 and further applied to the substrate 9. The tank 4 is supported so as to be displaceable in the vertical direction Z, and is displaced in the vertical direction Z by displacement driving means such as an electric motor and a hydraulic machine. The tank 4 further includes a liquid level sensor 8 that detects the liquid level of the coating liquid 7. The liquid level sensor 8 detects the height in the vertical direction Z of the liquid level of the coating liquid 7. The liquid level sensor 8 is realized by, for example, an optical sensor or an ultrasonic vibration sensor.

  The coating liquid 7 supplied from the tank 4 to the coating liquid supply hole 5 via the coating liquid supply pipe 6 is pressure generated according to the height of the liquid level in the tank 4 and capillary action generated in the coating liquid supply hole 5. According to the force by, it is extruded from the opening of the nozzle 3. Therefore, the height of the coating liquid 7 in the nozzle 3 or the height of the coating liquid 7 extruded from the opening of the nozzle 3 can be adjusted by adjusting the vertical position of the tank 4 to control the liquid level in the tank 4. Can be controlled.

  The cap coater system 1 further includes a control unit realized by a microcomputer or the like, and the control unit controls the displacement driving means described above. When the control unit controls the displacement driving means, the position of the nozzle 3 and the tank 4 in the vertical direction Z and the displacement of the surface plate 2 in the coating direction X are controlled. When the coating liquid 7 is applied, the coating liquid 7 is consumed and the liquid level of the coating liquid 7 in the tank 4 decreases with time, but the control unit controls the displacement driving means based on the detection result of the liquid level sensor 8. And the height of the coating liquid 7 extruded from the opening of the nozzle 3 can be controlled by adjusting the position of the tank 4 in the vertical direction Z.

  FIG. 2 is a time chart showing temporal changes of the positions of the surface plate 2, the tank 4 and the nozzle 3. As shown in FIG. The control of each position of the surface plate 2, the tank 4, and the nozzle 3 when applying the coating liquid will be described along the time chart of FIG.

  First, at time t1, the nozzle 3 is disposed below the substrate 9 with a predetermined interval, and the tank 4 is positioned below the application position (tank position when application is started). From time t1 to time t2, the surface plate 2 moves in one of the application directions X (hereinafter sometimes referred to as left), the nozzle 3 rises to the standby position, and the tank 4 rises to the liquid contact position. By raising the tank 4 to the liquid contact position, the coating liquid 7 is pushed out from the nozzle opening.

  From time t2 to time t3, the surface plate 2 moves further leftward to the application start position, and the nozzle 3 and the tank 4 hold the position of time 2. Note that the surface plate 2 maintains the position at the time t3 after the time t3 until the time t7 when the application is started.

  From time t3 to time t4, the nozzle 3 rises to the liquid contact position, and the tank 4 maintains the position at time t3. Thus, when the nozzle 3 is close to the substrate, the coating liquid is attached to the substrate side. The distance between the nozzle 3 and the substrate 9 at time t4 is preferably 5 μm or more and 50 μm or less, more preferably 5 μm or more and 10 μm or less, for example, 8 μm.

  From time t5 to time t6, the tank 4 and the nozzle 3 descend to the application position. Although the tank 4 and the nozzle 3 are lowered, the coating liquid extruded from the nozzle 3 is kept attached to the substrate 8 side. From time t6 to time t7, the tank 4 and the nozzle 3 hold the position at time t6.

  From time t7 to time t8, the surface plate 2 moves to the left at a constant speed from the application start position to the application end position, and the tank 4 rises from the application position to the application end position. The reason why the tank 4 rises during this period is that the liquid level of the coating liquid 7 in the tank 4 decreases due to the consumption of the coating liquid 7, so that this liquid level is kept constant. Thus, the coating liquid is applied to the substrate by moving the substrate that moves together with the surface plate 2 with the coating liquid 7 extruded from the nozzle 3 attached to the substrate 8 side.

  When the application is completed at time t8, the nozzle 3 and the tank 4 are lowered and the substrate 8 is moved to the right.

  In the present embodiment, between time t3 and time t4, the nozzle 3 is moved from below in a state in which the coating liquid containing the material serving as the organic functional layer is extruded from the nozzle disposed with the slit facing upward. The ascending speed when being brought close to the substrate 8 is set to 0.7 m / min or more. The higher rising speed of the nozzle 3 is preferable, and 1.0 m / min or more and 3.0 m / min is preferable.

  Conventionally, when the nozzle is raised at about 0.2 m / min between time t3 and time t4, the application start time is time t7, and in the previous process (time t3 to t4) Even if the rising speed is adjusted, it is difficult to expect that this adjustment will affect the film thickness of the coating film, but by setting the rising speed of the nozzle 3 to a predetermined range as shown in the example, The distance from the start of coating until the film thickness of the coating film becomes constant can be shortened.

  In addition, from time t5 to t6, it is preferable that the nozzle is lowered at a speed of 0.7 m / min or more after the nozzle is brought close to the substrate from below and before the nozzle and the substrate are relatively moved. . The lowering speed of the nozzle 3 is preferably higher, and more preferably 1.0 m / min to 3.0 m / min.

  Conventionally, when the nozzle is lowered at about 0.2 m / min between time t5 and time t6, the start time of application is time t7, and in the previous process (time t5 to t6) Even if the lowering speed is adjusted, it is difficult to expect that this adjustment will affect the film thickness of the coating film, but by setting the lowering speed of the nozzle 3 to a predetermined range as shown in the example, The distance from the start of coating until the film thickness of the coating film becomes constant can be shortened.

  Further, the relative speed when the nozzle 3 and the substrate are relatively moved is preferably 0.7 m / min or more, and more preferably 1.0 m / min or more and 3.0 m / min or less ( Time t7 to t8). Thus, by setting the relative speed when the nozzle 3 and the substrate are relatively moved within a predetermined range, the distance from the start of coating until the film thickness of the coating film becomes constant can be shortened.

  In addition, the distance between the nozzle 3 and the substrate when the nozzle 3 and the substrate 8 are relatively moved (from time t7 to time t8) is preferably 200 μm or more, and more preferably 300 μm or more and 350 μm or less. More preferably, it is 300 μm or more and 320 μm or less. By setting such an interval, it is possible to shorten the distance from the start of coating until the film thickness of the coating film becomes constant.

The organic electroluminescent element of this Embodiment is manufactured by the manufacturing method of the above-mentioned organic electroluminescent element.
The organic electroluminescent element of this embodiment can realize an element having a uniform film thickness by using the manufacturing method of the above-described embodiment.
Below, the layer structure of an organic EL element, the structure of each layer, and the manufacturing method of each layer are demonstrated.
As described above, the organic EL element includes at least an anode, a cathode, and a light emitting layer disposed between the anode and the cathode, and is provided between the anode and the light emitting layer and / or the light emitting layer. There may be another layer different from the light emitting layer between the cathode and the cathode, and a plurality of light emitting layers are arranged between the anode and the cathode, not limited to a single light emitting layer. Also good.

  Examples of the layer provided between the cathode and the light emitting layer include an electron injection layer, an electron transport layer, and a hole blocking layer. When both the electron injection layer and the electron transport layer are provided between the cathode and the light emitting layer, the layer close to the cathode is called an electron injection layer, and the layer close to the light emitting layer is called an electron transport layer.

  The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode. The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or the electron transport layer closer to the cathode. The hole blocking layer is a layer having a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer.

  The fact that the hole blocking layer has a function of blocking hole transport makes it possible, for example, to produce an element that allows only a hole current to flow, and confirm the blocking effect by reducing the current value.

  Examples of the layer provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer. When both the hole injection layer and the hole transport layer are provided, a layer close to the anode is referred to as a hole injection layer, and a layer close to the light emitting layer is referred to as a hole transport layer.

  The hole injection layer is a layer having a function of improving hole injection efficiency from the anode. The hole transport layer is a layer having a function of improving hole injection from the anode, the hole injection layer, or the hole transport layer closer to the anode. The electron blocking layer is a layer having a function of blocking electron transport. In the case where the hole injection layer and / or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron blocking layer.

  The fact that the electron blocking layer has a function of blocking electron transport makes it possible, for example, to produce an element that allows only electron current to flow and confirm the blocking effect by reducing the current value.

  The electron injection layer and the hole injection layer may be collectively referred to as a charge injection layer, and the electron transport layer and the hole transport layer may be collectively referred to as a charge transport layer.

A specific example of the layer structure that the organic EL element of the present embodiment can take is shown below.
a) Anode / light emitting layer / cathode b) Anode / hole transport layer / light emitting layer / cathode c) Anode / light emitting layer / electron transport layer / cathode d) Anode / hole transport layer / light emitting layer / electron transport layer / cathode e) Anode / charge injection layer / light emitting layer / cathode f) Anode / light emitting layer / charge injection layer / cathode g) Anode / charge injection layer / light emitting layer / charge injection layer / cathode h) Anode / charge injection layer / hole Transport layer / light emitting layer / cathode i) anode / hole transport layer / light emitting layer / charge injection layer / cathode j) anode / charge injection layer / hole transport layer / light emitting layer / charge injection layer / cathode k) anode / charge Injection layer / light emitting layer / charge transport layer / cathode l) anode / light emitting layer / electron transport layer / charge injection layer / cathode m) anode / charge injection layer / light emitting layer / electron transport layer / charge injection layer / cathode n) anode / Charge injection layer / hole transport layer / light emitting layer / charge transport layer / cathode o) anode / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode ) Anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode (here, the symbol “/” indicates that the layers sandwiching the symbol “/” are stacked adjacent to each other) The same shall apply hereinafter.)
The organic EL device of the present embodiment may have two or more light emitting layers, and examples of the organic EL device having two light emitting layers include the layer configuration shown in q) below. .
q) Anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / charge generation layer / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode Specifically, as an organic EL device having three or more light-emitting layers, (charge generation layer / charge injection layer / hole transport layer / light-emitting layer / electron transport layer / charge injection layer) is one repeating unit. Examples of the layer structure include two or more repeating units shown in the following r).
r) Anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / (the repeating unit) / (the repeating unit) /... / cathode In the above layer structures p) and q) The layers other than the anode, the electrode, the cathode, and the light emitting layer can be deleted as necessary.

  Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, indium tin oxide (abbreviated as ITO), molybdenum oxide, or the like.

  The organic EL element may be covered with a sealing member such as a sealing film for sealing or a sealing plate. When an organic EL element is provided on a substrate, an anode is usually disposed on the substrate side, but a cathode may be disposed on the substrate side.

  In the organic EL element of the present embodiment, in order to extract light from the light emitting layer to the outside, all the layers arranged on the side from which light is extracted are usually transparent with respect to the light emitting layer. As an example, an organic EL device having a layer structure of substrate / anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode / sealing member will be described. In the case of a so-called bottom emission type organic EL element that is taken out from the side, the substrate, the anode, the charge injection layer, and the hole transport layer are all transparent, and the so-called top that takes out light from the light emitting layer from the sealing member side. In the case of an emission type organic EL element, the electron transport layer, the charge injection layer, the cathode, and the sealing member are all transparent. As an example, an organic EL device having a structure of substrate / cathode / charge injection layer / electron transport layer / light emitting layer / hole transport layer / charge injection layer / anode / sealing member will be described. In the case of a bottom emission type device In the case of a top emission type organic EL element, all of the hole transport layer, the charge injection layer, the cathode and the sealing member are made transparent. Shall be transparent. Here, the degree of transparency is preferably such that the visible light transmittance between the outermost surface of the organic EL element on the light extraction side and the light emitting layer is 40% or more. In the case of an organic EL element that is required to emit light in the ultraviolet region or infrared region, one that exhibits a light transmittance of 40% or more in the region is preferable.

  In the organic EL element of the present embodiment, an insulating layer having a thickness of 2 nm or less may be provided adjacent to the electrode in order to further improve the adhesion to the electrode and the charge injection property from the electrode. In addition, a thin buffer layer may be inserted between the above-mentioned layers in order to improve adhesion at the interface or prevent mixing.

  The order of the layers to be laminated, the number of layers, and the thickness of each layer can be appropriately set in consideration of the light emission efficiency and the element lifetime.

  Next, the material and forming method of each layer constituting the organic EL element will be described more specifically.

<Board>
As the substrate, one that does not change in the process of manufacturing the organic EL element is suitably used. For example, glass, plastic, a polymer film, a silicon substrate, and a laminate of these are used. A commercially available substrate can be used as the substrate, and it can be produced by a known method.

<Anode>
In the case of an organic EL element configured to extract light from the light emitting layer through the anode, an electrode exhibiting translucency is used as the anode. As the electrode exhibiting translucency, thin films of metal oxides, metal sulfides, metals, and the like having high electrical conductivity can be used, and those having high light transmittance are preferably used. Specifically, a thin film made of indium oxide, zinc oxide, tin oxide, ITO, indium zinc oxide (abbreviated as IZO), gold, platinum, silver, copper, or the like is used. Among these, ITO, A thin film made of IZO or tin oxide is preferably used. Examples of a method for producing the anode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Further, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used as the anode.

  A material that reflects light may be used for the anode, and the material is preferably a metal, metal oxide, or metal sulfide having a work function of 3.0 eV or more.

  The film thickness of the anode can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm. .

<Hole injection layer>
As the hole injection material constituting the hole injection layer, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, phenylamine type, starburst type amine type, phthalocyanine type, amorphous carbon, polyaniline, And polythiophene derivatives.

  Examples of the method for forming the hole injection layer include film formation from a solution containing a hole injection material. The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole injection material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.

  As a film-forming method from a solution, it is preferable to form a film using the coating method of this Embodiment mentioned above, In addition to the coating method of this Embodiment, a spin coat method, a casting method, a micro gravure coat method And coating methods such as gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen printing method, flexographic printing method, offset printing method, and inkjet printing method. .

  The film thickness of the hole injection layer varies depending on the material used, and is set as appropriate so that the drive voltage and light emission efficiency are appropriate. If it is thick, the driving voltage of the element increases, which is not preferable. Therefore, the film thickness of the hole injection layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Hole transport layer>
As the hole transport material constituting the hole transport layer, polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine in a side chain or a main chain, a pyrazoline derivative, an arylamine derivative, a stilbene derivative, Triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p-phenylene vinylene) or derivative thereof, or poly (2,5-thienylene vinylene) or Examples thereof include derivatives thereof.

  Among these, hole transport materials include polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amine compound groups in the side chain or main chain, polyaniline or derivatives thereof, polythiophene or derivatives thereof, poly Polymeric hole transport materials such as arylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and polyvinylcarbazole or derivatives thereof are more preferred. , Polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

  The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material.

  The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a hole transport material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as anisole, tetralin and cyclohexylbenzene, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate.

  As a film forming method from a solution, it is preferable to form a film using the above-described coating method of the present embodiment. Besides the coating method of the present embodiment, the above-described film forming method of the in-hole injection layer The same coating method can be mentioned.

  As the polymer binder to be mixed, those that do not extremely inhibit charge transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, poly Examples thereof include vinyl chloride and polysiloxane.

  As the film thickness of the hole transport layer, the optimum value varies depending on the material to be used, the drive voltage and the light emission efficiency are appropriately set so as to have an appropriate value, and at least a thickness that does not cause pinholes is required. If the thickness is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the film thickness of the hole transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Light emitting layer>
The light emitting layer is usually formed of an organic substance that mainly emits fluorescence and / or phosphorescence, or an organic substance and a dopant that assists the organic substance. The dopant is added for the purpose of improving the luminous efficiency and changing the emission wavelength. The organic substance may be a low molecular compound or a high molecular compound. Examples of the light emitting material constituting the light emitting layer include the following dye materials, metal complex materials, polymer materials, and dopant materials.
(Dye material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds. Pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, pyrazoline dimers, quinacridone derivatives, coumarin derivatives, and the like.
(Metal complex materials)
Examples of the metal complex material include Al, Zn, Be, etc. as a central metal, or rare earth metals such as Tb, Eu, Dy, etc., and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, as a ligand, Examples include metal complexes having a quinoline structure, such as metal complexes having light emission from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzoates. Examples include a thiazole zinc complex, an azomethyl zinc complex, a porphyrin zinc complex, and a europium complex.
(Polymer material)
As polymer materials, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, the above dye materials and metal complex light emitting materials are polymerized. The thing etc. can be mentioned.

  Among the light-emitting materials, materials that emit blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.

  Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.

  Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

(Dopant material)
Examples of the dopant material include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like. In addition, the thickness of such a light emitting layer is usually about 2 nm-200 nm.

<Method for forming light emitting layer>
As a method for forming the light emitting layer, a method of applying a solution containing a light emitting material, a vacuum deposition method, a transfer method, or the like can be used. Examples of the solvent used for film formation from a solution include the same solvents as those used for forming a hole transport layer from the above solution.

  As a method for applying a solution containing a light emitting material, it is preferable to form a film using the above-described application method of this embodiment. Besides the application method of this embodiment, spin coating, casting, micro Gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, slit coating method, capillary coating method, coating method such as spray coating method and nozzle coating method, and gravure printing method, Application methods such as a screen printing method, a flexographic printing method, an offset printing method, a reverse printing method, and an inkjet printing method can be given. A printing method such as a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reverse printing method, and an ink jet printing method is preferable in that pattern formation and multicolor coating are easy. In the case of a low molecular compound exhibiting sublimability, a vacuum deposition method can be used. Furthermore, a method of forming a light emitting layer only at a desired place by laser transfer or thermal transfer can be used.

<Electron transport layer>
As the electron transport material constituting the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthra Quinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, etc. Can be mentioned.

  Among these, as an electron transport material, an oxadiazole derivative, benzoquinone or a derivative thereof, anthraquinone or a derivative thereof, a metal complex of 8-hydroxyquinoline or a derivative thereof, a polyquinoline or a derivative thereof, a polyquinoxaline or a derivative thereof, a polyfluorene Or a derivative thereof is preferable, and 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are further included. preferable.

  There are no particular restrictions on the method for forming the electron transport layer, but for low molecular weight electron transport materials, vacuum deposition from powder or film formation from a solution or a molten state can be used. Examples of the material include film formation from a solution or a molten state. In the case of forming a film from a solution or a molten state, a polymer binder may be used in combination. As a method of forming an electron transport layer from a solution, it is preferable to form a film using the coating method of the present embodiment described above. In addition to the coating method of the present embodiment, hole transport from the above solution is performed. A film formation method similar to the method of forming a layer can be given.

  The film thickness of the electron transport layer varies depending on the material used, and is set appropriately so that the drive voltage and the light emission efficiency are appropriate, and at least a thickness that does not cause pinholes is required, and is too thick. In such a case, the driving voltage of the element increases, which is not preferable. Therefore, the film thickness of the electron transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Electron injection layer>
As the material constituting the electron injecting layer, an optimum material is appropriately selected according to the type of the light emitting layer, and an alloy containing at least one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal, alkali A metal or alkaline earth metal oxide, halide, carbonate, or a mixture of these substances can be given. Examples of alkali metals, alkali metal oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride , Rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate, and the like. Examples of alkaline earth metals, alkaline earth metal oxides, halides and carbonates include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, Examples thereof include barium fluoride, strontium oxide, strontium fluoride, and magnesium carbonate. The electron injection layer may be composed of a laminate in which two or more layers are laminated, and examples thereof include LiF / Ca. The electron injection layer is formed by vapor deposition, sputtering, printing, or the like. The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

<Cathode>
As a material for the cathode, a material having a small work function, easy electron injection into the light emitting layer, and high electrical conductivity is preferable. Moreover, in the organic EL element which takes out light from the anode side, since the light from the light emitting layer is reflected to the anode side by the cathode, a material having a high visible light reflectance is preferable as the cathode material. For the cathode, for example, an alkali metal, an alkaline earth metal, a transition metal, a group III-B metal, or the like can be used. Examples of the cathode material include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like. A metal, two or more alloys of the metals, one or more of the metals, and one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin An alloy, graphite, or a graphite intercalation compound is used. Examples of alloys include magnesium-silver alloys, magnesium-indium alloys, magnesium-aluminum alloys, indium-silver alloys, lithium-aluminum alloys, lithium-magnesium alloys, lithium-indium alloys, calcium-aluminum alloys, and the like. it can. As the cathode, a transparent conductive electrode made of a conductive metal oxide, a conductive organic material, or the like can be used. Specifically, examples of the conductive metal oxide include indium oxide, zinc oxide, tin oxide, ITO, and IZO, and examples of the conductive organic substance include polyaniline or a derivative thereof, polythiophene or a derivative thereof, and the like. The cathode may be composed of a laminate in which two or more layers are laminated. In some cases, the electron injection layer is used as a cathode.

  The film thickness of the cathode is appropriately set in consideration of electric conductivity and durability, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

  Examples of the method for producing the cathode include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded.

<Insulating layer>
Examples of the material for the insulating layer include metal fluorides, metal oxides, and organic insulating materials. As an organic EL element provided with an insulating layer having a thickness of 2 nm or less, an organic EL element having an insulating layer having a thickness of 2 nm or less adjacent to the cathode and an insulating layer having a thickness of 2 nm or less adjacent to the anode are provided. Can be mentioned.

  The organic EL element of the present embodiment can be used as a planar light source, a light source of a segment display device and a dot matrix display device, and a backlight of a liquid crystal display device.

  When the organic EL element of the present embodiment is used as a planar light source, for example, a planar anode and a cathode may be arranged so as to overlap each other when viewed from one side in the stacking direction. In order to construct an organic EL element that emits light in a pattern as a light source of a segment display device, a method of installing a mask having a light-transmitting window formed in a pattern on the surface of the planar light source, There are a method in which the organic layer is formed extremely thick to make it substantially non-light-emitting, and a method in which at least one of the anode and the cathode is formed in a pattern. By forming organic EL elements that emit light in a pattern using these methods and wiring to selectively apply voltage to several electrodes, numbers, letters, simple symbols, etc. can be displayed. A segment type display device can be realized. In order to use the light source of the dot matrix display device, the anode and the cathode may be formed in stripes and arranged so as to be orthogonal to each other when viewed from one side in the stacking direction. In order to realize a dot matrix display device capable of partial color display and multi-color display, a method of separately coating a plurality of types of light emitting materials having different emission colors and a method using a color filter, a fluorescence conversion filter, and the like are used. Good. The dot matrix display device may be passively driven or may be actively driven in combination with a TFT or the like. These display devices can be used as display devices for computers, televisions, mobile terminals, mobile phones, car navigation systems, video camera viewfinders, and the like.

  Furthermore, the planar light source is a self-luminous thin type and can be suitably used as a backlight of a liquid crystal display device or a planar illumination light source. If a flexible substrate is used, it can be used as a curved light source or display device.

  The coating solution was applied on a glass substrate having a length in the coating direction X of 200 mm, a length in the width direction Y of 200 mm, and a thickness of 0.7 mm. As a solvent for the coating solution, a mixed solvent in which anisole and cyclohexylbenzene were mixed at a weight ratio of 1: 1 was used, and as a luminescent material, SW006 manufactured by Summation was used. This luminescent material is a material that emits white light. The ratio of the luminescent material in the coating solution was 0.8% by weight.

  The displacement of the surface plate, the tank and the nozzle was performed in the order shown in the time chart of FIG. The tank rising speed from time t1 to time t2 was 0.1 m / min, and the tank lowering speed from time t5 to time t6 was 0.25 m / min. The nozzle ascending speed from time t3 to t4 was 1.0 m / min, and the nozzle descending speed from time t5 to time t6 was 1.0 m / min. Furthermore, the speed of the surface plate from time t7 to time t8 was set to 0.5 m / min. Further, at time t7, the acceleration time until the speed of the surface plate reaches from 0 m / min to 0.5 m / min was set to 3 sec (seconds). The interval between the substrate and the nozzle from time t4 to time t5 was 8 μm, and the interval between the substrate and the nozzle from time t7 to time t8 was 220 μm.

(Comparative Example 1)
As Comparative Example 1, the coating liquid was applied in the same manner as in Example 1 except that only the nozzle ascending speed and descending speed were changed. The nozzle rising speed from time t3 to time t4 was 0.25 m / min, and the nozzle lowering speed from time t5 to time t6 was 0.05 m / min.

(Reference Example 1)
As Reference Example 1, the coating solution was applied in the same manner as in Comparative Example 1 except that only the ascending speed and descending speed of the tank were changed. The ascending speed of the tank from time t1 to time t2 was set to 3.0 m / min, and the descending speed of the tank from time t5 to time t6 was set to 3.0 m / min.

(Reference Example 2)
As Reference Example 2, the coating solution was applied in the same manner as Comparative Example 1 except that only the acceleration of the surface plate at time t7 was changed. At time t7, the acceleration time required for the platen speed to reach 0.5 m / min from 0 m / min was set to 0.1 sec.

(Evaluation)
Coating was performed in Example 1, Comparative Example 1, Reference Example 1, and Reference Example 2 using an optical interference film thickness meter (“3-dimensional non-contact surface shape measurement system MM557N-M100 type” manufactured by Ryoka Systems Co., Ltd.). The film thickness of the coated film was measured. The measurement results are shown in FIG. In FIG. 3, the horizontal axis represents the length of the substrate in the coating direction, and the vertical axis represents the film thickness of the coating film. One end of the substrate in the coating direction was set to 0 mm.

  As shown in FIG. 3, in comparison with Comparative Example 1, it was observed that in Example 1, the film thickness suddenly decreased from the application start position, and the film thickness of the coating film became constant as soon as possible from the start of application. did. Thus, it was confirmed that the distance from the start of coating to the film thickness of the coating film becomes shorter by adjusting the rising speed and the lowering speed of the nozzle in the process before time t7 when the application starts. Moreover, the distance from the start of coating to the film thickness of the coating film becomes constant by changing the ascending speed and descending speed of the tank and the acceleration of the surface plate from the change in the film thickness of Reference Example 1 and Reference Example 2. It was confirmed that it became shorter.

(Reference Example 3)
As Reference Example 3, the coating solution was applied in the same manner as Comparative Example 1. Although the result of Reference Example 3 shown in FIG. 4 is different from the result of Comparative Example 1, this difference seems to be caused by a subtle difference in the initial setting that occurs when setting the apparatus.

(Reference Example 4)
As Reference Example 4, the coating solution was applied in the same manner as in Reference Example 3 except that the distance between the nozzle and the substrate when applying the coating solution was varied. The distance between the substrate and the nozzle from time t7 to t8 was 320 μm.

(Reference Example 5)
As Reference Example 5, the coating solution was applied in the same manner as Reference Example 3 except that the distance between the nozzle and the substrate when applying the coating solution was changed. The interval between the substrate and the nozzle from time t7 to time t8 was 70 μm.

(Reference Example 6)
As Reference Example 6, the coating solution was applied in the same manner as Reference Example 3 except that only the speed of the platen when applying the coating solution and the application position of the tank 4 were changed. The speed of the surface plate from time t7 to time t8 was 1.0 m / min, and the tank application position was lowered by 2 mm. The reason why the application position of the tank 4 is changed is that the film thickness becomes thicker when the speed is increased.

(Evaluation)
The film thickness of the coating film applied in Reference Examples 3 to 6 was measured with the above-described optical interference film thickness meter. The measurement results are shown in FIG. In FIG. 4, the horizontal axis represents the length in the coating direction of the substrate, and the vertical axis represents the film thickness of the coating film. One end of the substrate in the coating direction was set to 0 mm.

  As shown in FIG. 4, in Reference Examples 3 to 5, only the distance between the nozzle and the substrate when applying the coating liquid is different, but the distance between the substrate and the nozzle is the widest 320 μm among the three. Then (Reference Example 4), it was confirmed that the distance from the beginning of coating until the film thickness of the coating film became constant was shortened. Also, as in Reference Example 6, when the speed of the platen when applying the coating liquid was increased to 1.0 m / min, it was confirmed that the distance from the start of coating until the film thickness of the coating film became constant was shortened did.

  On the same glass substrate as in Example 1, the same coating solution as in Example 1 was applied. The displacement of the surface plate, the tank and the nozzle was performed in the order shown in the time chart of FIG. The ascending speed of the tank from time t1 to time t2 was set to 3.0 m / min, and the descending speed of the tank from time t5 to time t6 was set to 3.0 m / min. The nozzle ascending speed from time t3 to time t4 was 1.0 m / min, and the nozzle descending speed from time t5 to time t6 was 1.0 m / min. Furthermore, the speed of the surface plate from time t7 to t8 was 1.0 m / min. Further, at time t7, the acceleration time until the speed of the surface plate reaches from 0 m / min to 1.0 m / min was set to 0.1 sec. The distance between the substrate and the nozzle from time t7 to time t8 was 320 μm.

(Comparative Example 2)
As Comparative Example 2, the coating solution was applied in the same manner as Comparative Example 1. Although the result of Comparative Example 2 shown in FIG. 5 is different from the result of Comparative Example 1, this difference seems to be caused by a subtle difference in the initial setting that occurs when setting the apparatus.

(Evaluation)
The film thickness of the coating film applied in Example 2 and Comparative Example 2 was measured using the above-described optical interference film thickness meter. The measurement results are shown in FIG. In FIG. 5, the horizontal axis represents the length of the substrate in the coating direction, and the vertical axis represents the film thickness of the coating film. One end of the substrate in the coating direction was set to 0 mm.

  As shown in FIG. 5, it was confirmed that the distance from the start of coating until the film thickness of the coating film became constant was shortened by using the conditions of Example 2.

It is a figure which shows typically the cap coater system 1 used in order to form a light emitting layer. 4 is a time chart showing temporal changes in positions of the surface plate 2, the tank 4 and the nozzle 3. It is a figure which shows the film thickness of the coating film applied in Example 1, Comparative Example 1, Reference Example 1, and Reference Example 2. It is a figure which shows the film thickness of the coating film apply | coated by the reference examples 3-6. It is a figure which shows the film thickness of the coating film apply | coated in Example 2 and Comparative Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cap coater system 2 Surface plate 3 Nozzle 4 Tank 5 Coating liquid supply hole 6 Coating liquid supply pipe 7 Coating liquid 8 Liquid level sensor 9 Substrate X Coating direction Y Width direction Z Vertical direction

Claims (5)

A method for producing an organic electroluminescent device by laminating at least an anode, a cathode, and one or more organic functional layers positioned between the anode and the cathode,
In a state where the coating liquid containing the material to be the organic functional layer is extruded from a nozzle arranged with the slit facing upward, the nozzle is brought close to the substrate from below, and the coating liquid is attached to the substrate side. Forming a coating film by relatively moving the nozzle and the substrate, and forming the organic functional layer,
A method for producing an organic electroluminescent element, wherein an ascending speed when the nozzle is brought close to the substrate from below is 0.7 m / min or more.   2. The nozzle according to claim 1, wherein the nozzle is lowered at a speed of 0.7 m / min or more after the nozzle is brought close to the substrate from below and before the nozzle and the substrate are relatively moved. Manufacturing method of organic electroluminescent element.   The method for producing an organic electroluminescent element according to claim 1, wherein a relative speed when the nozzle and the substrate are relatively moved is 0.7 m / min or more.   The method for manufacturing an organic electroluminescence element according to claim 1, wherein a distance between the nozzle and the substrate when the nozzle and the substrate are relatively moved is 200 μm or more.   The organic electroluminescent element manufactured with the manufacturing method of the organic electroluminescent element as described in any one of Claims 1-4.

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