JP2007095595A - Forming method of functional layer, organic semiconductor element, light emitting element, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a forming method of a functional layer capable of coating uniformly on a substrate a coating liquid containing a low molecular material or a coating liquid containing a polymer material yet having low viscosity. <P>SOLUTION: This is a method of forming a functional layer in which a functional liquid dissolved or dispersed with a functional material in a solvent is coated on a substrate, and then, the functional liquid is dried and the functional layer consisting of the functional material is formed. Smectite is added in the functional liquid in the forming method of this functional layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a functional layer, an organic semiconductor element, a light emitting element, and an electronic device.

  An organic electroluminescence device (hereinafter referred to as an organic EL device) includes a functional layer including at least a light emitting layer containing a light emitting material and a hole injection / transport layer containing a hole injection / transport material. And the second electrode layer, and an element that emits light by recombination of carriers injected from these two electrodes in the light emitting layer. This organic EL element has the characteristics of being thin and light, and the light emitting layer and the hole injection / transport layer are uniformly formed by using a coating method such as an ink jet method or a spin coating method. Since it can be manufactured by forming, application to a large flat panel display is expected.

The coating liquid in the above coating method is prepared by dissolving or dispersing a light emitting material or a hole injection / transport material in a solvent. As these light emitting materials or hole injection / transport materials, high molecular weight organic materials have been conventionally used. For example, in Patent Document 1 below, a polymer material such as polytetrahydrothiophenylphenylene is used as a hole injecting / transporting material, and a polymer material such as cyanopolyphenylene vinylene is used as a red light emitting material. A method of manufacturing an organic EL display manufactured by applying a coating liquid containing a polymer material is disclosed.
However, since it is difficult to achieve high purity or to narrow the molecular weight distribution of the polymer material, there are variations in the characteristics expressed by the polymer material, and it is difficult to obtain stable light emission characteristics. There was a problem.

In order to solve the above problem, Patent Document 2 discloses a method for producing an organic electroluminescent device in which a high-purity, easy-to-purify, low-molecular material having no distribution in molecular weight is dissolved in a solvent and this coating solution is applied. Is disclosed.
Japanese Patent Laid-Open No. 10-12377 JP-A-2005-78896

  However, depending on the original viscosity of the solvent, the coating liquid containing low molecular weight materials generally has a low viscosity. For example, this coating liquid can be used on a substrate with high liquid repellency or affinity with low molecular weight materials. When the coating is applied on a substrate having a low viscosity, the coating solution is repelled due to the low viscosity, which makes it difficult to form a uniform film. In general, a coating liquid containing a low molecular material has a small correlation between the concentration of the low molecular material and the viscosity of the coating liquid, and it is difficult to adjust the viscosity according to the concentration of the low molecular material. Therefore, even if the concentration of the low molecular material is increased, it is still difficult to form a uniform film.

  The present invention has been made in view of the above circumstances, and even when a coating solution containing a low molecular material or a polymer material is contained, a coating solution having a low viscosity can be uniformly applied onto a substrate. It aims at providing the formation method of a functional layer. It is another object of the present invention to provide an organic semiconductor element, a light emitting element, and an electronic device that include a functional layer having a uniform thickness.

In order to achieve the above object, the present invention employs the following configuration.
In the method for forming a functional layer of the present invention, the functional layer made of the functional material is dried by applying a functional liquid obtained by dissolving or dispersing the functional material in a solvent onto a substrate and then drying the functional liquid. A method of forming the method is characterized in that smectite is added to the functional liquid.

According to said structure, it becomes possible to raise the viscosity of a functional liquid easily by adding a smectite to a functional liquid. Thereby, when apply | coating a functional liquid on a base | substrate, a functional liquid is uniformly apply | coated on a base | substrate, without being repelled. Then, by drying the functional liquid, it is possible to form a functional layer having a substantially uniform thickness.
The substrate to which the functional liquid is applied may, for example, have a liquid-repellent treatment applied to the application surface, and a functional layer different from the functional layer is formed in advance, and the surface of this different functional layer May be a coated surface. In addition, as a means for applying the functional liquid, a spin coating method or an ink jet method can be used.

  In the method for forming a functional layer of the present invention, the smectite is preferably synthetic smectite, pentonite, montmorillonite, saponite, hectorite, biderite, stevensite, or a mixture containing at least two of these, particularly synthetic smectite. Is preferably used.

  Any of the above smectites can be uniformly dispersed in the functional liquid because of its good dispersibility in water, aqueous solvents, polar organic solvents, or nonpolar organic solvents. In particular, synthetic smectites can be made separately into hydrophilic smectites that can be dispersed in water or aqueous solvents, or lipophilic smectites that can be dispersed in organic solvents, depending on the synthesis method. Any solvent can be uniformly dispersed.

In addition, the organic semiconductor element of the present invention includes a functional layer containing at least a functional material and smectite.
The above functional layer contains smectite together with a functional material that exhibits the functionality of the functional layer. Since this smectite acts as a stabilizer in the functional layer, the functionality of the functional layer is stably expressed. It becomes possible to make it.

In the light emitting device of the present invention, a functional layer including a light emitting layer containing at least a light emitting material and smectite is disposed between the first electrode layer and the second electrode layer. .
The light emitting layer contains smectite together with the light emitting material, and this smectite functions as at least a stabilizer in the light emitting layer, so that good light emitting characteristics can be ensured without deterioration of the light emitting layer.

According to another aspect of the present invention, there is provided an electronic apparatus including the above-described organic semiconductor element or the above-described light-emitting element.
According to said structure, the electronic device provided with the favorable functional layer or the light emitting layer can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
(Organic EL device)
Hereinafter, an organic EL element as a light-emitting element according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of the organic EL element of this embodiment. In FIG. 1, an organic EL element 1 includes a substrate 2, an anode (first electrode layer) 4 and a cathode (second electrode layer) 7 provided on one surface side of the substrate 2, and these anode 4 and cathode 7. An organic EL layer (functional layer) 3 sandwiched therebetween is provided. An element control unit con is connected to the anode 4 and the cathode 7 so that an arbitrary voltage can be applied to the electrodes 4 and 7. The organic EL layer 3 includes a hole injection / transport layer 5 and a light emitting layer 8 as main components.

  Here, the organic EL element 1 shown in FIG. 1 has a form in which output light from the light emitting layer 8 is extracted from the substrate 2 side to the outside of the apparatus, and the substrate 2 is made of a transparent or translucent material that can transmit light. Yes. Examples of such materials include transparent glass, quartz, sapphire, or transparent synthetic resins such as polyester, polyacrylate, polycarbonate, polyether ketone, and the like. In particular, an inexpensive soda glass is preferably used as a material for forming the substrate 2. Although not shown in the present embodiment, elements such as wiring and thin film transistors can be formed on the substrate 2.

  Similarly, the anode 4 is made of a transparent or translucent conductive material that can transmit light. Specifically, what consists of indium tin oxide (ITO) is employ | adopted.

  On the other hand, in the case where the emitted light is extracted from the side opposite to the substrate 2, the material constituting the substrate 2 may be opaque. In this case, surface oxidation is performed on a ceramic sheet such as alumina or a metal sheet such as stainless steel. It is possible to use an insulating treatment such as a thermosetting resin or a thermoplastic resin. In this case, the anode 4 can be formed of a light shielding or light reflecting material.

  The hole injection / transport layer 5 provides a function of improving device characteristics such as the light emission efficiency and lifetime of the light emitting layer 8. That is, by providing the hole injection / transport layer 5, electrons moving in the light emitting layer 8 are efficiently blocked, and an effect of increasing the recombination probability of holes and electrons in the light emitting layer 8 can be obtained. As the hole injection / transport material (functional material) for forming the hole injection / transport layer, for example, polyphenylene vinylene whose polymer precursor is polytetrahydrothiophenylphenylene, 1,1-bis- (4-N, Examples include N-ditolylaminophenyl) cyclohexane, tris (8-hydroxyquinolinol) aluminum, polystyrene sulfonic acid, a mixture of polyethylenedioxythiophene and polystyrene sulfonic acid (PEDOT / PSS), and the like.

As the light emitting material (functional material) of the light emitting layer 8, low-molecular organic light emitting dyes and polymer light emitters, that is, light emitting materials such as various fluorescent materials and phosphorescent materials, and organic electroluminescence such as Alq3 (aluminum chelate complex). Although materials can be used, a low molecular weight light emitting material is particularly preferable. Specifically, CBP (4,4-dicarbazole-4,4-biphenyl) shown in [Chemical Formula 1] as a host material and Ir shown in [Chemical Formula 2] as a guest material are used as low-molecular light-emitting materials. A mixture of (ppy) ₃ (tris (4-phenylpyridinolato) iridium (III)) can be preferably used. The emission color can be changed by adjusting the amount of Ir (ppy) ₃ added.

Here, the light emitting layer 8 contains smectite as a stabilizer and a binder. By adding smectite, crystallization of a low molecular weight light-emitting material can be prevented. Further, even when the temperature of the light emitting layer 8 rises, the light emitting layer 8 does not collapse, thereby preventing leakage of the applied voltage and preventing a short circuit between the anode 4 and the cathode 7. Further, since smectite is electrically inactive, it does not particularly affect the light emitting characteristics of the light emitting material.
The smectite is preferably synthetic smectite, pentonite, montmorillonite, saponite, hectorite, biderite, stevensite, or a mixture containing at least two of these, and synthetic smectite that can easily control the amount of impurities is used. It is preferable.

  The content of smectite in the light emitting layer 8 is preferably in the range of 5% by mass to 25% by mass, and more preferably in the range of 5% by mass to 10% by mass. When the smectite content is less than 5% by mass, the function as a stabilizer and a binder cannot be sufficiently achieved. On the other hand, when the content exceeds 25% by mass, the transport of carriers for causing the light emitting layer to emit light is inhibited, which is not preferable.

The cathode 7 is a metal electrode made of aluminum (Al), magnesium (Mg), gold (Au), silver (Ag), or the like. In the organic EL element 1, it is preferable to provide a sealing member that covers the cathode 7, and further, between the anode 4 and the substrate 2, the organic EL layer 3 including the anode 4 and the cathode 7 from the substrate 2 side. On the other hand, a sealing layer for blocking the entry of the atmosphere can also be provided. The sealing layer provided on the light extraction side is formed of a transparent material such as ceramic, silicon nitride, silicon oxynitride, or silicon oxide. Among these, silicon oxynitride is preferable from the viewpoint of transparency and gas barrier properties. The thickness of the sealing layer is preferably smaller than the wavelength of light emitted from the light emitting layer 8 (for example, 0.1 μm).
In addition, a sealing layer is formed on the cathode 7 by applying an adhesive made of a thermosetting resin, a thermosetting resin, or an ultraviolet curable resin, and then a sealing substrate is stacked and heated or irradiated with ultraviolet rays to form a sealing layer. May be cured to bond the sealing substrate and the base material.

  The organic EL element 1 of the present embodiment can be applied to either an active matrix type or a passive matrix type as its driving method, and emits light by supplying current to the organic EL layer 3 through the electrode layers 4 and 7. The layer 8 emits light so that light can be emitted to the outer surface side of the substrate 2.

(Manufacturing method of organic EL element)
Next, a method for manufacturing the organic EL element 1 of FIG. 1 will be described. The method for manufacturing the organic EL element 1 includes the method for forming a functional layer of the present invention.
First, a translucent substrate 2 made of glass or the like is prepared, and an anode 4 made of ITO is formed on the substrate 2. The surface of the anode 4 is desirably cleaned in advance by UV ozone treatment or the like.

Subsequently, a hole injection / transport layer 5 is formed on the anode 4. Here, the coating liquid (functional liquid) containing the above-described hole injection / transport material is used, this coating liquid is applied onto the anode 4 by spin coating, and the coating liquid is dried, whereby hole injection / The transport layer 5 is formed.
As the coating liquid, for example, a mixture of polyethylene dioxythiophene and polystyrene sulfonic acid (PEDOT / PSS) as the hole injection / transport material described above in water can be used. In addition, as the coating solution, the above-described hole injection / transport material may be dissolved in a polar solvent. Examples of polar solvents include water, isopropyl alcohol (IPA), normal butanol, γ-butyrolactone, N-methylpyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI) and its derivatives, carbitol acetate And glycol ethers such as butyl carbitol acetate.

  The above coating solution is applied to the anode 4 by spin coating. Thereafter, the target hole injection / transport layer 5 is obtained by annealing by heating and drying (200 ° C., 30 minutes) on a hot plate, for example.

Subsequently, a light emitting layer 8 (functional layer) is formed on the hole injection / transport layer 5 as a substrate. Here, as in the case of the hole injection / transport layer, a coating liquid (functional liquid) containing the above-described light emitting material is used, and this coating liquid is applied onto the hole injection / transport layer 5 by a spin coating method. The light emitting layer 8 is formed by drying the coating liquid.
The coating liquid is configured to include the above-described light emitting material, smectite, and a solvent.
As the light-emitting material, a mixture of CBP and Ir (ppy) ₃ can be used. As the smectite, any of those described above can be used, and it is particularly preferable to use synthetic smectite. Synthetic smectites can be made into hydrophilic smectites that can be dispersed in water or aqueous solvents, or lipophilic smectites that can be dispersed in organic solvents, depending on the synthesis method. Any of these can be uniformly dispersed.

Examples of the solvent include water-compatible alcohols such as water, methanol, and ethanol. As organic solvents, N, N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylimidazoline (DMI), dimethyl sulfoxide (DMSO), xylene, toluene, cyclohexylbenzene, 2,3-dihydrobenzofuran, etc. It can be illustrated. Two or more of these aqueous solvents and organic solvents may be appropriately mixed.
Here, it is desirable to use a solvent having a low solubility in the hole injection / transport layer 5 as a solvent for the coating liquid when forming the light emitting layer. For example, when the hole injection / transport layer 5 is made of a PEDOT / PSS mixture, it is desirable to use xylene, toluene, ethylbenzene, or the like as the solvent.

The concentration of the luminescent material in the coating liquid is preferably in the range of 1% by mass or more and 2% by mass or less as a mass ratio to the solvent. The concentration of smectite in the coating liquid is preferably in the range of 0.1% by mass to 0.5% by mass, more preferably in the range of 0.1% by mass to 0.2% by mass as a mass ratio to the solvent. . Further, when a mixture of CBP and Ir (ppy) ₃ is used as the light emitting layer, the mixing ratio thereof is preferably in the range of CBP: Ir (ppy) ₃ = 90: 10 to 95: 5 by mass ratio.
Further, the viscosity of the coating liquid depends on the material of the hole injection / transport layer 5 serving as the substrate, the liquid repellency of the surface of the hole injection / transport layer 5, the original viscosity of the solvent, the material of the light emitting material, and the like. The viscosity at 25 ° C. is preferably about 1 mPa · s to 10 mPa · s, more preferably about 2 mPa · s to 5 mPa · s.

  The above coating solution is applied to the hole injection / transport layer 5 as a substrate by a spin coating method. Thereafter, vacuum drying (30 minutes at 10 −4 Torr) is performed, and the target light emitting layer 8 is obtained by annealing on a hot plate at 100 ° C. for 60 minutes.

  Subsequently, aluminum is formed on the formed light emitting layer 8 to obtain the cathode 7. Then, predetermined wiring formation with the element control part con etc. is performed, and the organic EL element 1 shown in FIG. 1 is obtained.

  As described above, according to the method for manufacturing an organic EL element of the present embodiment, the viscosity of the coating liquid can be easily increased by adding smectite to the coating liquid containing the light emitting material. Thus, when the coating liquid is applied onto the hole injection / transport layer 5, the coating liquid is uniformly applied without being repelled. And the light emitting layer 8 with a substantially uniform thickness can be formed by drying a coating liquid. The light emitting layer 8 of the organic EL device 1 manufactured as described above contains smectite, and since this smectite acts as a stabilizer and a binder in the light emitting layer 8, the light emitting layer 8 is not deteriorated and is good. Luminescence characteristics can be exhibited.

[Second Embodiment]
(Organic EL device)
Next, an organic EL element as a light emitting element according to a second embodiment of the present invention will be described with reference to the drawings. Of the constituent elements of the present embodiment shown in FIG. 2, the same constituent elements as those of the first embodiment shown in FIG. Or simply explain.
FIG. 2 is a schematic cross-sectional view of the organic EL element of this embodiment. The organic EL element 21 shown in FIG. 2 includes a substrate 2, an anode (first electrode layer) 4 and a cathode (second electrode layer) 7 provided on one surface side of the substrate 2, and these anode 4 and cathode 7. An organic EL layer (functional layer) 23 sandwiched therebetween is provided. An element control unit con is connected to the anode 4 and the cathode 7 so that an arbitrary voltage can be applied to both electrodes. The organic EL layer 23 is composed of a light emitting layer 28.

  Here, the organic EL element 1 shown in FIG. 2 is configured to take out the output light from the light emitting layer 28 from the substrate 2 side to the outside of the apparatus, and the substrate 2 is made of a transparent or translucent material that can transmit light. Yes. Similarly, the anode 4 is made of a transparent or translucent conductive material that can transmit light. Specifically, a material made of ITO is employed.

  The surface of the anode 4 on the light emitting layer 28 side is subjected to plasma surface treatment using oxygen having a fluorine content of 1% by mass or less. By performing such plasma surface treatment, a metal fluoride is formed on the surface of the anode 4 on the side of the light emitting layer 28, thereby expanding the band gap of the anode 4 and increasing the ionization potential. become. Thereby, even if the light emitting layer 28 is directly formed on the anode 4, it becomes possible to reduce the barrier between the anode 4 and the light emitting layer 28, and positive holes are reliably formed between the anode 4 and the light emitting layer 28. An injection is performed.

As in the first embodiment, the light emitting material (functional material) of the light emitting layer 28 is a low molecular weight organic light emitting dye or polymer light emitting material, that is, a light emitting material such as various fluorescent materials or phosphorescent materials, Alq3 ( An organic electroluminescent material such as an aluminum chelate complex) can be used, and in particular, a low molecular weight light emitting material can be used. As a low molecular light emitting material, a mixture of CBP and Ir (ppy) ₃ can be preferably used. In addition, the light emitting layer 28 contains smectite as a stabilizer and a binder as in the first embodiment. The smectite content may be the same as in the first embodiment.

  The cathode 7 is a metal electrode made of aluminum (Al), magnesium (Mg), gold (Au), silver (Ag), or the like. In addition, in the organic EL element 21, it is preferable to provide a sealing member that covers the cathode 7 as in the first embodiment, and further, between the anode 4 and the substrate 2, the anode 4 from the substrate 2 side, A sealing layer for blocking air from entering the organic EL layer 3 including the cathode 7 can be provided. In addition, a sealing layer is formed on the cathode 7 by applying an adhesive made of a thermosetting resin, a thermosetting resin, or an ultraviolet curable resin, and then a sealing substrate is stacked and heated or irradiated with ultraviolet rays to form a sealing layer. May be cured to bond the sealing substrate and the base material.

  As in the first embodiment, the organic EL element 1 of the present embodiment can be applied to either an active matrix type or a passive matrix type as its driving method, and the organic EL layer is interposed through the electrode layers 4 and 7. By supplying a current to the light source 23, the light emitting layer 28 can emit light, and light can be emitted to the outer surface side of the substrate 2.

(Manufacturing method of organic EL element)
Next, a method for manufacturing the organic EL element 21 of FIG. 2 will be described. The method for manufacturing the organic EL element 21 includes the method for forming a functional layer of the present invention.
First, a translucent substrate 2 made of glass or the like is prepared, and an anode 4 made of ITO is formed on the substrate 2. The surface of the anode 4 is desirably cleaned in advance by UV ozone treatment or the like.

Subsequently, plasma surface treatment is performed on the surface of the anode 4. This plasma surface treatment is a plasma surface treatment using oxygen having a fluorine content of 1% by mass or less. Fluorine in oxygen is preferably supplied by being contained in oxygen as a fluororesin such as carbon tetrafluoride high-limit visual field polytetrafluoroethylene.
More specifically, for example, in a down flow type plasma apparatus, the output is 500 W to 1 kW, the oxygen flow rate is 50 ml / min to 100 ml / min, the carbon tetrafluoride flow rate is 0.5 ml / min to 1 ml / min, and the treatment time is 5 Plasma surface treatment may be performed on the surface of the anode 4 under the conditions of 10 minutes to 10 minutes. Further, plasma treatment may be performed by placing polytetrafluoroethylene in a quartz tube for generating plasma of a plasma apparatus to serve as a fluorine source, and setting the output, oxygen flow rate, and treatment time to the same conditions as described above.

Subsequently, a light emitting layer 28 (functional layer) is formed on the anode 4 after the plasma treatment as a substrate. Here, a light-emitting layer 28 is formed by using a coating liquid (functional liquid) containing a light-emitting material, applying the coating liquid onto the anode 4 by spin coating, and drying the coating liquid.
The coating liquid is configured to include the above-described light emitting material, smectite, and a solvent. The specific composition of the coating liquid may be the same as that in the first embodiment.
However, in the case of the present embodiment, since the coating liquid is applied on the anode 4 that has been plasma-treated and improved in liquid repellency, the viscosity of the coating liquid is the same as or higher than that of the first embodiment. It is preferable to set the viscosity to be high. More specifically, the viscosity at 25 ° C. is preferably about 1 mPa · s to 10 mPa · s, more preferably about 2 mPa · s to 5 mPa · s. The viscosity can be adjusted, for example, by the smectite concentration.

  The above coating solution is applied to the anode 4 as a substrate by a spin coating method. Then, vacuum drying (30 minutes at 10-4 Torr) is performed, and the target light emitting layer 28 is obtained by annealing on a hot plate at 100 ° C. for 60 minutes.

  Subsequently, aluminum is formed on the formed light emitting layer 28 to obtain the cathode 7. Then, predetermined wiring formation with the element control part con etc. is performed, and the organic EL element 21 shown in FIG. 2 is obtained.

  As described above, according to the method for manufacturing the organic EL element 21 of the present embodiment, the viscosity of the coating liquid can be easily increased by adding smectite to the coating liquid containing the light emitting material. Thereby, when apply | coating a coating liquid on the anode 4 by which the liquid repellency was improved by plasma processing, a coating liquid is apply | coated uniformly, without being repelled. Then, by drying the coating liquid, the light emitting layer 28 having a substantially uniform thickness can be formed. The light emitting layer 28 of the organic EL device 21 thus manufactured contains smectite, and this smectite acts as a stabilizer and a binder in the light emitting layer 28, so that the light emitting layer 28 is not deteriorated and is good. Luminescence characteristics can be exhibited.

[Third Embodiment]
(Method for manufacturing organic EL device)
Next, a method for manufacturing an organic EL device including a light emitting element according to a third embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the light emitting layer forming step described later corresponds to the functional layer forming method according to the present invention.
The manufacturing method of the present embodiment includes a partition wall forming step, a plasma processing step, a hole injection / transport layer forming step, a surface modification step, a light emitting layer forming step, a cathode forming step, and a sealing step. It is comprised.

  As shown in FIG. 3, in the partition forming step, an inorganic bank layer is formed on the first electrode layer 11 made of ITO or the like formed on the substrate 10 on which TFTs (not shown) are provided in advance as necessary. A bank layer (partition wall) 12 separating each pixel region is formed by sequentially laminating 12a and the organic bank layer 12b.

The inorganic bank layer 12a is formed by forming an inorganic film (not shown) such as SiO ₂ , TiO ₂ , SiN on the entire surface of the substrate 10 and the transparent electrode 11 by, for example, CVD, sputtering, vapor deposition or the like. The film is formed by patterning by etching or the like to provide an opening 13 a in the pixel region on the first electrode layer 11. However, at this time, the inorganic bank layer 12 a is left up to the peripheral edge of the transparent electrode 11. Further, the film thickness of the inorganic bank layer 12a is preferably in the range of 50 to 200 nm, particularly 150 nm.

  Next, an organic film (not shown) such as an acrylic resin or a polyimide resin is formed on the entire surface of the substrate 10, the first electrode layer 11, and the inorganic bank layer 12a by spin coating, dip coating, or the like. Then, the organic film is etched to form the opening 13b to form the organic bank layer 12b. The opening 13b of the organic bank layer 12b is preferably formed slightly wider than the opening 13a of the inorganic bank layer 12a as shown in FIG. Thereby, an opening 13 penetrating the inorganic bank layer 12a and the organic bank layer 12b is formed on the first electrode layer 11.

Next, in the plasma treatment step, a region showing lyophilicity and a region showing liquid repellency are formed on the surface of the bank layer 12. This plasma treatment process is roughly divided into a preheating process, a lyophilic process for making the entire surface lyophilic, a lyophobic process for making the organic bank layer 12b lyophobic, and a cooling process.
First, in the preheating step, the substrate 10 including the bank layer 12 is heated to a predetermined temperature.
Next, in the lyophilic step, the bank layer 12 is subjected to a plasma treatment (O ₂ plasma treatment) using oxygen as a reactive gas in an air atmosphere. Conditions for the O ₂ plasma treatment are, for example, plasma power of 100 to 800 kW, oxygen gas flow rate of 50 to 100 cc / min, substrate transfer speed of 0.5 to 10 mm / sec, and substrate temperature of 70 to 90 ° C. By this O ₂ plasma treatment, hydroxyl groups are introduced into the exposed surfaces of the transparent electrode 11 and the inorganic bank layer 12a and the entire surface of the organic bank layer 12b, thereby imparting lyophilicity.

Next, in the lyophobic process, the bank layer 12 is subjected to plasma treatment (CF ₄ plasma treatment) using tetrafluoromethane (carbon tetrafluoride) as a reactive gas in the air atmosphere. The conditions of the CF ₄ plasma treatment are, for example, the conditions of plasma power of 100 to 800 kW, tetrafluoromethane (carbon tetrafluoride) gas flow rate of 50 to 100 SCCM, substrate transfer speed of 0.5 to 10 mm / sec, and substrate temperature of 70 to 90 ° C. To do. The processing gas is not limited to tetrafluoromethane (carbon tetrafluoride) but may be other fluorocarbon-based gas. With the CF ₄ plasma treatment, fluorine groups are introduced into the organic bank layer 12b to which lyophilicity has been imparted in the previous step, thereby imparting liquid repellency. The acrylic resin, polyimide resin, and the like constituting the organic bank layer 12b can be easily made liquid-repellent by irradiating the fluorocarbon in a plasma state so that the hydroxyl group is easily replaced with a fluorine group. On the other hand, the first electrode layer 11 and the inorganic bank layer 12a are also somewhat affected by this CF ₄ plasma treatment, but do not significantly affect the affinity.
And as a cooling process, the board | substrate 10 heated for the plasma processing is cooled to room temperature.

As described above, by sequentially performing the O ₂ plasma treatment and the CF ₄ plasma treatment on the organic bank layer 12a and the inorganic bank layer 12b, the bank layer 12 has an ink-philic region and an ink repellent region. Easy to install.

Next, in the hole injecting / transporting layer forming step, the coating liquid 15 containing the hole injecting / transporting layer material is discharged to the opening 13 on the first electrode layer 11 by an inkjet method, and then heat treatment is performed. Thus, the hole injection / transport layer 16 is formed. In addition, after this hole injection / transport layer formation process, it is preferable to carry out in inert gas atmospheres, such as a nitrogen atmosphere and argon atmosphere without a water | moisture content and oxygen. As shown in FIG. 4, the inkjet head 14 is filled with a coating liquid 15 containing a hole injection / transport layer material, the ejection nozzle of the inkjet head 14 is opposed to the opening 13, and the inkjet head 14 and the substrate 10 are relative to each other. While being moved, the liquid material 15 in which the amount of liquid per droplet is controlled is discharged from the inkjet head 14 onto the first electrode layer 11.
As the coating liquid 15 used here, one having the same composition as in the first and second embodiments can be used, but the hole injection / transport material is red (R), green (G), blue. The same material may be used for each light emitting layer of (B), and may be changed for each light emitting layer.

The discharged coating liquid 15 spreads over the first electrode layer 11 and the inorganic bank layer 12a subjected to the lyophilic process in the opening 13. Further, even if the coating liquid 15 deviates from a predetermined discharge position and is discharged onto the organic bank layer 12 b, the organic bank layer 12 b is not wetted by the coating liquid 15, and the repelled coating liquid 15 is in the opening 13. Roll in.
The discharge amount of the coating liquid 15 is determined by the size of the opening 13, the thickness of the hole injection / transport layer to be formed, the concentration of the hole injection / transport layer material in the coating liquid 15, and the like. Further, the coating liquid 15 may be discharged not only once but also into the same opening 13 in several times.

  Next, as shown in FIG. 5, the hole-injecting / transporting layer 16 is formed by heat-treating the discharged coating liquid 15 to evaporate the solvent contained in the coating liquid 15. This heat treatment may be performed in the same manner as in the first and second embodiments.

Next, in the light emitting layer forming step, a coating liquid 17 having the same composition as in the first and second embodiments is used, and this coating liquid 17 is applied onto the hole injection / transport layer 16 by an inkjet method as shown in FIG. To discharge.
Note that as the light emitting material for forming the light emitting layer, all the materials corresponding to the respective colors of red (R), green (G), and blue (B) can be used without using the light emitting materials described above. As for one or two of them, a conventionally used single-component light-emitting material, for example, a fluorescent light-emitting material (fluorescent material) can also be used. Examples of such single-component light emitting materials include fluorene polymer derivatives, (poly) paraphenylene vinylene derivatives, polyphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole, polythiophene derivatives, perylene dyes, coumarin dyes, rhodamine dyes. A pigment | dye etc. can be used.
However, in the case of the present embodiment, since the coating liquid 17 is applied by the ink jet method, it is preferable that the viscosity is applicable to the ink jet method. More specifically, the viscosity at 25 ° C. is preferably about 1 mPa · s to 10 mPa · s, more preferably about 2 mPa · s to 5 mPa · s. The viscosity can be adjusted, for example, by the smectite concentration.

  Then, after these coating liquids 17 are discharged onto the hole injection / transport layer 16, the light emitting layers 18 a, 18 b and 18 c are sequentially formed as shown in FIG. Form. The drying process and the heat process may be performed under the same conditions as those described in the first and second embodiments.

Next, in the cathode forming step, as shown in FIG. 8, a cathode 19 (second electrode layer) is formed on the entire surface of the light emitting layers 18a, 18b, 18c and the organic bank layer 12b. The cathode 19 may be formed by stacking a plurality of materials. For example, it is preferable to form Ca, Ba or the like having a small work function on the side close to the light emitting layer. Further, an Al film, an Ag film, a Mg / Ag laminated film, or the like having a higher work function than the cathode layer on the lower side (light emitting layer side) may be formed on the upper side (sealing side). Further, a protective layer such as SiO, SiO ₂ or SiN may be provided on the cathode 19 to prevent oxidation.

  Finally, in the sealing step, a sealing material made of a thermosetting resin or an ultraviolet curable resin is applied to the entire surface of the cathode 19 to form the sealing layer 20. Further, a sealing substrate (not shown) is stacked on the sealing layer 20. The sealing step is preferably performed in an inert gas atmosphere such as nitrogen, argon, or helium. If it is carried out in the air, when a defect such as a pinhole has occurred in the reflective layer, water, oxygen or the like may enter the cathode 19 from the defective portion and the cathode 19 may be oxidized, which is not preferable. In this way, an organic EL device 100 as shown in FIG. 8 is obtained.

In the organic EL device 100 obtained in this way, as in the first and second embodiments, the light emitting layer 17 contains smectite, and this smectite is contained in the light emitting layer 17 as a stabilizer and a binder. Therefore, it is possible to develop good light emission characteristics without deteriorating the light emitting layer 17.
Moreover, according to the manufacturing method of the organic EL device of this embodiment, the viscosity of the coating liquid can be easily increased by adding smectite to the coating liquid containing the light emitting material. Thereby, when the coating liquid is applied onto the hole injection / transport layer 16, the coating liquid is uniformly applied without being repelled. And the light emitting layer 17 with substantially uniform thickness can be formed by drying a coating liquid.

  The organic EL device of the present invention is not limited to the above embodiment, and various modifications can be made. For example, although a full color display is provided by providing R, G, and B light emitting layers, only one single color light can be emitted and used as a light source. In particular, when the organic EL device 100 is used as a light source, the R, G, and B light-emitting layers 18a, 18b, and 18c can emit light simultaneously to produce a white light source that emits white light.

  Next, a specific example of an electronic apparatus including the organic EL device 100 as a display unit will be described. FIG. 9A is a perspective view showing an example of a mobile phone. In FIG. 9A, reference numeral 600 indicates a mobile phone body, and reference numeral 601 indicates the organic EL device as a display unit. FIG. 9B is a perspective view illustrating an example of a portable information processing apparatus such as a word processor or a personal computer. In FIG. 9B, reference numeral 700 denotes an information processing apparatus, reference numeral 701 denotes an input unit such as a keyboard, reference numeral 703 denotes an information processing apparatus body, and reference numeral 702 denotes the organic EL device as a display unit. FIG. 9C is a perspective view showing an example of a wristwatch type electronic device. In FIG. 9C, reference numeral 800 denotes a watch body, and reference numeral 801 denotes the organic EL device as a display unit. According to this embodiment, an electronic apparatus including a display device having excellent light emission characteristics is obtained.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Organic EL element of the first example)
First, an ITO was formed on a transparent substrate, and this was further patterned to form an anode. Next, UV ozone treatment was performed to clean the surface of the anode.

Next, as a hole injection / transport material, a (PEDOT / PSS) dispersion (PEDOT: PSS = 1: 20 (mass ratio)) is prepared. A coating solution for the transport layer was prepared. The solid content concentration of PEDOT: PSS in the coating liquid was 3% by mass.
And this coating liquid was apply | coated on the anode by the spin coat method. Thereafter, a hole injecting / transporting layer having a thickness of 50 nm was formed by heat treatment on a hot plate at a temperature of 200 ° C. for about 30 minutes.

Next, a mixed material of CBP and Ir (ppy) ₃ was prepared as a light emitting material, and this mixed material was dissolved in xylene to prepare a coating solution for forming a light emitting layer. The coating liquid was prepared so that the mixing ratio of the mixed material was CBP: Ir (ppy) ₃ = 90: 10 in terms of mass ratio, and the total concentration was 2 mass% with respect to xylene. Furthermore, lipophilic smectite (product name: Lucentite SAN) manufactured by Coop Chemical Co., Ltd. was added to the coating solution at a different concentration. Three types of smectite concentrations were prepared so as to be 0.1 mass%, 0.2 mass%, and 0.5 mass% with respect to xylene.
And each coating liquid was dripped on the positive hole injection / transport layer, and spin coat application was performed. Thereafter, vacuum drying (30 minutes at 10 −4 Torr) was performed, and annealing was further performed on a hot plate at 100 ° C. for 60 minutes to form a light emitting layer having a thickness of 50 nm. At this time, the formation state of the light emitting layer was observed. The results are shown in Table 1.

Next, a LiF film having a thickness of 0.5 nm was formed on the entire surface of the light emitting layer, and an Al film having a thickness of 150 nm was further formed thereon, thereby forming a cathode made of a LiF / Al laminated film. . Thereafter, an adhesive made of a thermosetting resin is applied on the cathode to form a sealing layer, and then a sealing substrate (glass substrate) is stacked and heated to cure the sealing layer, thereby sealing the substrate. Were joined. Thus, the organic EL element shown in FIG. 1 was manufactured.
The voltage of 10V was applied between the anode and cathode of the manufactured organic EL element, and the light emission characteristics were examined. The results are shown in Table 2.

(Organic El element of the second example)
Fluorine plasma treatment is performed on the surface of the anode, the light emitting layer, the cathode and the sealing layer are laminated on the anode, and the sealing substrate is further stacked. Thus, the organic EL element shown in FIG. 2 was manufactured. Fluorine plasma treatment is performed on the ITO surface (anode surface) using a vacuum plasma apparatus under the conditions of oxygen flow rate: 100 cc / min, hydrogen tetrafluoride flow rate: 1 cc / min, plasma output: 1 kW, treatment time: 10 min. Processed.
The formation state of the light emitting layer was observed in the same manner as in the first example. Further, the light emission characteristics were examined by applying a voltage of 10 V between the anode and the cathode. The results are shown in Table 1 and Table 2, respectively.

As shown in Table 1, in the coating liquid to which smectite was not added, a light emitting layer having a desired film thickness was formed on PEDOT / PSS, but a light emitting layer was formed on the anode subjected to the fluorine plasma treatment. Was not.
On the other hand, when using a coating liquid to which smectite is added in an amount of 0.1% by mass, 0.2% by mass, and 0.5% by mass, respectively, in either case of the first example or the second example, the desired A light-emitting layer having a film thickness could be formed.

Further, as shown in Table 2, using the coating liquid to which no smectite was added and the coating liquid having an addition amount of 0.1% by mass and 0.2% by mass among the coating liquid to which smectite was added. In the formed organic EL element, although light emission was confirmed, light emission was not obtained when 0.5% by mass of smectite was added. This is presumably because the amount of smectite added was large and the amount of smectite remaining in the formed light emitting layer also increased, which hindered carrier transport necessary for causing the organic EL device to emit light.
From the above results, it was found that when smectite is added, it is necessary to suppress the concentration to a certain threshold value or less and to adjust the concentration so that it can be applied to a liquid-repellent substrate.

  Although the present invention has been described above with reference to the embodiments, the technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, although an example in which smectite is added to the light emitting layer has been described in the present invention, smectite may be added to another functional layer such as a hole injection / transport layer. The functional layer includes not only the hole injection / transport layer and the light emitting layer but also the electron injection / transport layer within the technical scope of the present invention. In the present embodiment, the organic EL element is described as an example of the organic semiconductor element. However, the present invention can of course be applied to a semiconductor element having an organic semiconductor thin film.

FIG. 1 is a schematic cross-sectional view showing an organic EL element according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing an organic EL element according to a second embodiment of the present invention. FIG. 3 is a process diagram illustrating a method for manufacturing an organic EL device according to a third embodiment of the present invention. FIG. 4 is a process diagram illustrating a method for manufacturing an organic EL device according to a third embodiment of the present invention. FIG. 5 is a process diagram illustrating a method for manufacturing an organic EL device according to a third embodiment of the present invention. FIG. 6 is a process diagram illustrating a method for manufacturing an organic EL device according to a third embodiment of the present invention. FIG. 7 is a process diagram illustrating a method for manufacturing an organic EL device according to a third embodiment of the present invention. FIG. 8 is a process diagram illustrating a method for manufacturing an organic EL device according to a third embodiment of the present invention. FIG. 9 is a perspective view illustrating an example of an electronic device including the organic EL element of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 21 ... Organic EL element (Light emitting element (organic semiconductor element)) 3, 23 ... Functional layer 4, 11 ... Anode (first electrode layer), 7, 19 ... Cathode (second electrode layer), 8, 18a, 18b, 18c, 28 ... light emitting layer, 600, 700, 800 ... electronic equipment

Claims (5)

A method of forming a functional layer made of the functional material by applying a functional liquid obtained by dissolving or dispersing a functional material in a solvent on a substrate and then drying the functional liquid,
A method for forming a functional layer, comprising adding smectite to the functional liquid.   2. The method for forming a functional layer according to claim 1, wherein the smectite is synthetic smectite, pentonite, montmorillonite, saponite, hectorite, biderite, stevensite, or a mixture containing at least two of these.   An organic semiconductor element comprising a functional layer containing at least a functional material and smectite.   A light-emitting element, wherein a functional layer including a light-emitting layer containing at least a light-emitting material and smectite is disposed between the first electrode layer and the second electrode layer. An electronic apparatus comprising the organic semiconductor element according to claim 3 or the light-emitting element according to claim 4.

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