JP4779808B2 - Transparent conductive film forming method and organic electroluminescent device manufacturing method - Google Patents

Description

  The present invention relates to a method for forming a transparent electrode using a sputtering method, and also relates to a method for manufacturing an organic electroluminescent element using the method for forming a transparent electrode.

  The fields of application of transparent conductive films are diversified, such as optical communications, semiconductor lasers, various displays, recording media, consumer devices (digital cameras, projectors, mobile phones, lenses, mirrors, lamps, etc.). Has become an important requirement for stability during mass production, such as yield improvement, and for film performance when forming a multilayer film.

  An organic electroluminescent element has a structure in which an organic light emitting layer is sandwiched between two electrodes, and the organic light emitting layer emits light by passing a current between the electrodes. One of the electrodes must be transparent. It has been proposed to use a transparent conductive film made of indium / tin oxide (ITO) or the like as the transparent electrode (for example, Patent Documents 1, 2, 3, and 4).

  In the top emission type organic electroluminescence device, an electrode on the side opposite to the substrate and a transparent electrode are used. At this time, by forming a transparent conductive film on the metal thin film, It has been proposed to reduce protection and wiring resistance. In order to use the transparent conductive film as a cathode, it is proposed to sandwich a buffer layer between the organic light emitting layer and the transparent conductive film for the purpose of protecting the underlying organic light emitting layer and reducing the electron injection barrier. . For the formation of the transparent conductive film, the conventional deposition methods, as well as the plasma and ion beam assisted deposition methods, ion plating methods, ion beam sputtering methods, etc. that have been used in recent years for optical communications are mainly used. In addition, a wet method such as a sol / gel method or a spray method may be used. On the other hand, there is a sputtering method as a method used in mass production apparatuses in thin film manufacturing processes such as semiconductors, flat panel displays, and electronic components. The sputtering method is widely used as a method suitable for mass production because the film formation rate and film composition are stable and uniform film formation on a large area substrate is possible. Furthermore, it has become mainstream because of its high uniformity of film thickness, conductivity and transparency, and excellent fine etching characteristics.

The known literature is shown below.
JP 2003-901158 A JP 2001-250678 A Japanese Patent No. 2850906 JP 2005-68501 A

  When a conductive film is patterned on a substrate by a vapor deposition method, the vapor deposition method deposits particles on the substrate with only thermal energy, and thus the energy of particles incident on the substrate is about 0.1 eV. On the other hand, when a transparent conductive film is patterned on a substrate by sputtering, the energy of particles incident on the substrate is as high as about 600 eV. In general, when the energy of particles incident on the substrate is about 50 eV or more, there are problems that particles enter the substrate, atoms constituting the substrate are knocked out, or defects are generated in the substrate.

  In particular, when a transparent conductive film is formed on an organic thin film by sputtering, the molecular structure (bond breaking) of the organic thin film is caused by scattering and collision of high-energy particles such as recoil Ar plasma, γ electrons, and target particles. There is a problem that the light emission potential inherent to the organic light-emitting material is reduced due to the destruction.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a transparent conductive film forming method in which a mask is provided on a substrate and a transparent conductive film is patterned on the substrate by a sputtering method. A grid is provided, the magnet is rod-shaped, a plurality of magnets are arranged radially on the grid, the polarity of the magnet is made to coincide with the center direction of the grid, and a voltage is applied to the grid The transparent conductive film forming method is characterized in that a transparent conductive film made of a target forming material is patterned on the substrate by a sputtering method.

According to a second aspect of the present invention, the plurality of rod-shaped magnets are loaded into a cavity of a magnet loading jig provided with a cavity in a non-magnetic material, and the magnet loading jig is provided on a grid. was the transparent conductive film forming method of claim 1, wherein.

As the invention according to claim 3, in a transparent conductive film formed, the substrate and the transparent conductive film forming method according to claim 1 or 2, characterized in that it is cooled by the Peltier element did.

According to a fourth aspect of the present invention, there is provided an organic electroluminescent device comprising at least a first electrode, an organic light emitting layer, and a second electrode in this order on a substrate, and causing the organic light emitting layer to emit light by passing a current between the electrodes. In the manufacturing method, at least one of the first electrode and the second electrode is patterned by the method according to any one of claims 1 to 3 .

According to a fifth aspect of the invention, there is provided a top emission type organic electroluminescence which comprises at least a reflective electrode, an organic light emitting layer and a transparent electrode on a base material in this order, and causes the organic light emitting layer to emit light by passing a current between the electrodes. In the element manufacturing method, a transparent electrode was formed by the method according to any one of claims 1 to 3. A method for manufacturing a top emission organic electroluminescence element was provided.

Further, as an invention according to claim 6 , in the method for producing an organic electroluminescent element according to claim 4 or claim 5 , a step of dissolving or dispersing the organic light emitting layer forming material in a solvent to obtain an ink, It was set as the manufacturing method of the organic electroluminescent element characterized by including the process of forming an organic light emitting layer on a base material by the letterpress reverse offset printing method using this ink.

  By forming a transparent conductive film on a substrate by sputtering using a grid provided with a magnet, recoil Ar ions emitted by colliding Ar ions with the target, γ electrons as secondary electrons, target Of the particles, the incidence of γ electrons, which are secondary electrons, on the substrate can be reduced. Since the direction of movement of γ electrons entering the substrate is bent by the magnetic field formed by the magnet, the incidence of γ electrons on the substrate is reduced.

  By reducing the incidence of γ electrons on the substrate, for example, when the substrate has an organic thin film and a transparent conductive film is formed on the organic thin film, the organic thin film is not destroyed. A transparent conductive film can be formed thereon.

  Further, by using rod-shaped magnets, arranging them radially on the grid, and matching the polarities of the magnets, it has become possible to efficiently reduce the incidence of γ electrons on the substrate.

  In addition, when patterning a transparent conductive film with a metal mask using a sputtering method, thermal radiation (infrared radiation) and further leakage plasma are accompanied by a rise in temperature caused by an increase in plasma charged particle density on the target surface due to plasma confinement. Since a part of the mask is incident on the mask surface, the mask is thermally expanded and deformed. In the present invention, when the transparent conductive film is formed by sputtering, the substrate is cooled by the Peltier element, so that the temperature rise of the substrate and the mask can be prevented. It became possible to suppress thermal deformation. Therefore, an accurate pattern can be formed on the substrate.

  Further, by loading the plurality of rod-shaped magnets in a cavity of a magnet loading jig provided with a cavity in a non-magnetic material, and providing the magnet on a grid, by adjusting the number of rod-shaped magnets, It has become possible to easily adjust the strength of the magnetic field formed on the grid. In addition, a plurality of rod-shaped magnets can be easily arranged in parallel without causing repulsion.

  In addition, by using the method for forming a transparent conductive film of the present invention in a method for producing an organic electroluminescent element, it becomes possible to form a transparent electrode without damaging the substrate, and an organic electroluminescent element having good light emitting characteristics can be obtained. I was able to get it. In particular, in a top emission type organic electroluminescent device, it becomes possible to form a transparent electrode on an organic thin film such as an organic light emitting layer without damaging it, and an organic electroluminescent device with good emission characteristics and low driving voltage is obtained. I was able to.

  The letterpress reverse offset printing method uses a blanket, fixes the blanket to the blanket cylinder, and transfers the patterned ink on the blanket surface to the transfer target. The pattern and thickness of the ink are controlled. There is an advantage that it is easy to do. In the method for producing an organic electroluminescent element, an organic light emitting layer having an excellent pattern shape could be obtained by forming an organic light emitting layer by using a letterpress reverse printing method.

  Hereinafter, embodiments of the present invention will be described.

Applications of the transparent conductive film used in the present invention are diverse. In particular, when it is used as an electrode for an optoelectronic device, it must satisfy the requirements according to the usage conditions of various devices. In particular, the transparent conductive film-forming material must be a material that satisfies both electrical characteristics and optical characteristics in the visible light region. As a transparent conductive film forming material in the present invention, indium oxide-based ITO (added Sn as a dopant to In ₂ O ₃ ), SnO ₂ (adding dopant) in the tin oxide system, and AZO (ZnO in the zinc oxide system) are used. In addition, Al can be added as a dopant), GZO (adding Ga as a dopant to ZnO), IZO (adding In as a dopant to ZnO), and the like can be used.

  Besides these, it is possible to use CdO-based and gallium oxide-based materials. However, the CdO system is difficult to put into practical use because Cd has toxicity. Gallium oxide-based transparent conductive films also have a number of features such as having a wide band gap. However, like indium, gallium is not an abundant material from the viewpoint of resources. As described above, the transparent conductive film forming material has a social background in which the environmental aspect must be given top priority as a material design guideline.

ITO is called Indium tin oxide, but its mother crystal is In ₂ O ₃ . ITO (In ₂ O ₃ : Sn) having a composition in which Sn is added in an amount of 5 to 10 wt% in terms of oxide is transparent like an insulator but has high conductivity (10 × 10 ³ S / cm) and absorption. Few. Transparency and conductivity are related to each other, but there is no one-to-one correspondence. Transparency means that the structural integrity of the In ₂ O ₃ crystal is high and the number of electron trap levels in the band gap is very small, but the atoms in the crystal are coordinate points of the crystal system (lattice position). It is determined by whether or not it is correctly positioned. The In ₂ O ₃ reagent is yellowish white, and a transparent conductive film is obtained by vapor deposition or sputtering in an atmosphere containing a slight amount of oxygen (partial pressure is 10 × 10 ⁻¹ Pa or less). However, as a compound, it is easy to let go of oxygen, and it is easily reduced by heating in a vacuum or in a reducing atmosphere containing several percent of hydrogen. As the reduction proceeds, the color changes from blue-black to black and further to brown. . The conductivity is expressed by substituting with In atoms or Sn atoms of the mother crystal or by forming a film under conditions that do not give sufficient and sufficient oxygen atoms.

The physical meaning of transparency of ITO can be attributed to the fact that the band gap as a semiconductor is in the vicinity of the short wavelength limit of 400 nm in the visible region. However, this is not enough, and in order to ensure high transparency, there are few or negligible levels at which electrons are resident at room temperature in the band gap. Such bandgap levels are derived from lattice defects due to oxygen vacancies, In atoms other than Sn atoms substituted at the In position, or Sn atoms or atomic groups (clusters). It must be easy to form a lattice. In ₂ O ₃ satisfies this requirement unless the film is formed in an atmosphere having extremely weak oxidizing properties. In fact, with In ₂ O _{3, if} the glass substrate temperature is set to about 300 ° C., a well-prepared X-ray diffraction pattern with a narrow half-value width from a thickness of several tens of nanometers, even under atmospheric conditions where oxygen is slightly insufficient Indicates. Even if Sn is added, this characteristic that is easily crystallized is not lost up to about several tens of percent. This is a feature that is greatly different from the SnO ₂ film and the ZnO film.

  Next, it shows about the transparent conductive film formation method of this invention. In the present invention, a transparent electrode is formed on a substrate by a sputtering method, and an ion beam sputtering method, a direct current sputtering method, a high frequency sputtering method, a magnetron sputtering method, or the like can be used as the sputtering method.

  Magnetron sputtering has a high current density, and ions collide with electrons at a high energy of 600 eV, so that a transparent conductive film can be formed at high speed. In addition, the average free path of the sputtered particles is long because of the low pressure, and the thin film can be deposited by collecting the sputtered particles on the substrate opposed to the target. However, when a transparent conductive film is formed on an organic thin film because of a high energy process, recoil Ar plasma, γ electrons, and accelerated Target particles collide with the underlying organic thin film to cause a large damage. have.

  A schematic diagram of a DC magnetron sputtering apparatus used for forming the transparent conductive film of the present invention is shown in FIG. In FIG. 1, a grid (2) is provided between a substrate (1) and a target (3). The grid (2) is provided with a magnet (7). The target (3) is fixed to the packing plate (OFC) (4), and a cathode magnet (5) is provided on the surface of the packing plate (4) opposite to the target (3). ing. Note that the inside of the apparatus is in a vacuum state during film formation.

  A voltage is applied to the grid (2). By applying a voltage to the grid, the plasma charged particles can be captured (disappeared) by neutralizing the polarity of the plasma charged particles. Accordingly, the frequency of incidence of plasma charged particles on the mask can also be reduced, which acts as a carrier trap mechanism.

  The present invention is characterized in that a grid (2) having a magnet (7) is provided between a target (1) made of a transparent conductive film forming material and a substrate. By installing a grid (2) with a magnet (7) between the target and the substrate, a magnetic field is formed, and γ electrons are attracted to the magnetic lines of force formed by the magnet, so that sputtering damage and substrate charge-up due to electron collision with the substrate are performed. Can be suppressed. In particular, when the substrate has an organic thin film on the surface and a transparent conductive film is formed on the surface of the organic thin film, the sputter damage of the organic thin film can be reduced and the transparent conductive film can be formed on the organic thin film.

  The magnetic field line in the present invention is a magnetic field line formed by a magnet installed on the grid, and forms a radial circle at the installation point of each magnet with respect to the grid center. In the present invention, the polarities of the grid magnets only have to be the same polarity in the center direction of the grid.

  The plasma in the present invention is a quasi-neutral state in which electrons and atoms are captured around the nucleus of the atoms and molecules constituting the gas. In such a gas, energy is given from the outside by discharge or the like. The electrons are free to swing off the attractive force of the nuclei, and the gas is in a state where the electrons and nuclei (positive ions) are separated. This is plasma. Plasma is said to be the fourth state of substances aligned in solid, liquid and gas.

The Ar ion in the present invention is a positive ion formed when Ar gas in a quasi-neutral state is turned into plasma by discharge or the like.

The γ electrons that are secondary electrons are high-energy electrons that are emitted when plasma electrons collide with Ar gas or target particles.

  FIG. 2 shows an example of the layout of magnets on the grid. As shown in FIG. 2, the magnet (7) has a rod shape, a plurality of magnets are arranged radially on the grid (2), and the polarities of the magnets are made to coincide with the center direction of the magnets arranged radially. Is preferred. By attaching a magnet so that the same poles face each other on the top of the grid, it is possible to efficiently form a repulsive magnetic field and attract γ electrons partially leaked from the grid to the magnetic field lines due to the repulsive magnetic field.

  A known permanent magnet can be used as the magnet. The shape of the magnet is preferably a rod, and may be a polygonal column such as a triangular column or a quadrangular column, or may be a cylinder or an elliptical column. Further, when a bar-shaped magnet is used, a plurality of bar-shaped magnets may be connected in series, or a plurality of bar-shaped magnets may be bundled. By using a bundle of a plurality of bar-shaped magnets as a magnet, the magnetic flux density of the magnet can be easily changed by changing the number of bar-shaped magnets.

  FIG. 3 shows a magnet loading jig for bundling a plurality of bar magnets (7) of the present invention. As shown in FIG. 3, the magnet loading jig of the present invention has a structure in which a columnar cavity is provided in a nonmagnetic material. One or a plurality of bar-shaped magnets can be placed in series in the columnar cavity. In FIG. 3, four rod-shaped magnets are loaded in series in one cavity. In the magnet loading jig, a plurality of columnar cavities are provided, and a magnet can be loaded into each cavity. The magnet loading jig is provided on the grid in a form in which a magnet is loaded.

  When bundling a plurality of bar magnets with their polarities aligned, it takes time to create a bunch because each magnet repels. By using the magnet loading jig of the present invention and inserting the required number of magnets into the magnet loading jig, a plurality of bar magnets can be easily arranged in parallel, and the magnetic flux density of the magnet can be easily changed. Can do.

  The magnet loading jig of the present invention is made of a nonmagnetic material. As the non-magnetic material, known materials can be used, but it is preferable to use an Al alloy because it is lightweight. By reducing the weight of the magnet loading jig, the deflection of the grid due to the weight of the magnet and the magnet loading jig can be reduced when the magnet loading jig is installed on the grid.

  The columnar cavity of the magnet loading jig may be a polygonal columnar shape such as a triangular column or a quadrangular column, or may be a cylinder or an elliptical column. It is appropriately selected depending on the shape of the bar magnet.

  FIG. 4 is an explanatory view of the periphery of the substrate in the transparent conductive film forming method of the invention. The substrate (1) is sandwiched between the mask (15) and the mask frame (16) and the magnet holder (14) and has a close contact structure. In the substrate (1), a transparent conductive film is patterned on the surface in close contact with the mask according to the opening shape of the mask. In the transparent conductive film forming method of the present invention, the substrate is cooled by the Peltier element during the formation of the transparent conductive film. The Peltier element is provided on the magnet holder.

  The Peltier element is a semiconductor element that can easily cool the substrate and the mask by installing the Peltier element on the top of the contact substrate under vacuum. The provision of the Peltier element does not require any major modification of the apparatus, and the substrate and the mask can be easily cooled.

  When a temperature difference is given to both ends of an object, an electromotive force is always generated unless it is a superconductor. This phenomenon is called the Seebeck effect, and a thermocouple used for temperature measurement is used in the vicinity. If an external circuit is connected to the high temperature end and the low temperature end of the substance, current can be generated by this thermoelectromotive force and taken out as electric power. On the contrary, when two kinds of substances are joined and current is passed, heat is reversibly generated or absorbed at the joining point depending on the direction of the current. This is called the Peltier effect, and the Seebeck effect described above is a thermoelectric phenomenon integrated with the front and back. Heating and cooling can be done reversibly simply by reversing the current, and the response speed is extremely slow. As thermoelectric cooling and electronic cooling, cooling of semiconductor lasers, highly sensitive infrared detectors, CCDs, etc. Widely used in medical equipment and other fields that require precise temperature control and local rapid cooling. The two thermo-electric conversion processes, the Seebeck effect and the Peltier effect, are collectively referred to as thermoelectric conversion.

  When the Peltier element uses a P-type semiconductor and an N-type semiconductor, the P-type thermoelectric power has a positive sign, the N-type thermoelectric power has a negative sign, and the relative thermoelectric power is very large, so that a large thermoelectric effect can be obtained. . FIG. 5 shows an explanatory sectional view of the Peltier element. As shown in FIG. 5, in the Peltier element, P-type semiconductors (44a) and N-type semiconductors (44b) are alternately arranged in a saddle shape between metal substrates (43) between ceramic substrates (42). Thus, an element having a cooling or heat absorption capability is obtained. This element is called a Peltier element because it utilizes the Peltier effect that causes a current difference to flow by causing a current to flow.

  Next, the manufacturing method of the organic electroluminescent element of this invention is described. In the organic electroluminescent element of the present invention, a first electrode, an organic light emitting layer, and a second electrode are provided in this order on a substrate. Further, a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, a charge generation layer, and the like are provided as necessary between the first electrode and the second electrode as a light emission auxiliary layer. The first electrode, the organic light emitting layer, and the second electrode provided on the substrate are sealed for the purpose of protecting both the electrodes, the organic light emitting layer, and the like from moisture in the environment. As sealing, a method of bonding a glass cap or a metal cap to a base material, or a method of covering a base material provided with a first electrode, an organic light emitting layer, or a second electrode with a barrier layer or the like can be used. .

  One of the first electrode and the second electrode is an anode, and the other is a cathode. An organic electroluminescent element is a device that emits light from an organic light emitting layer by passing an electric current between electrodes. A method of taking out emitted light from a substrate side is a bottom emission method, and a method of taking out light from a side opposite to a substrate. This is called the top emission method. In the bottom-down method, the layer on the substrate side with respect to the organic light emitting layer needs to be transparent in order to transmit light emitted from the organic light emitting layer. That is, the base material and the first electrode need to have transparency. On the other hand, in a top emission type organic electroluminescent device, the layer on the side opposite to the substrate with respect to the organic light emitting layer needs to be transparent in order to transmit light emitted from the organic light emitting layer. That is, the second electrode needs to have transparency, and it is necessary to prevent light from being blocked by sealing.

  FIG. 5 shows an explanatory cross-sectional view of a top emission type organic electroluminescent element. In FIG. 6, a reflective electrode (21) is formed as a first electrode on the base material (20), a partition wall (22) is formed between the reflective electrodes (21), and the reflective electrode (21) is formed on the reflective electrode (21). A hole transport layer (23) and an organic light emitting layer (24a, 24b, 24c) are provided in this order, and further, an electron injecting protective layer (25), a second layer on the organic light emitting layer (24a, 24b, 24c). Transparent electrodes (26) are provided as two electrodes. Then, a reflective electrode (21), a partition wall (22), a hole transport layer (23), an organic light emitting layer (24a, 24b, 24c), an electron injecting protective layer (25), and a transparent electrode (26) were provided. The base material is sealed with a barrier layer (27), a resin layer (28), and a sealing base material (29).

  In the top emission type organic electroluminescence device of the present invention, as the substrate (20), a glass substrate or a plastic film or sheet can be used. If a plastic film is used, an organic light emitting element can be manufactured by winding, and the element can be provided at low cost. As the plastic film material, for example, polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate and the like can be used. Moreover, you may laminate | stack other gas-barrier films, such as a ceramic vapor deposition film, a polyvinylidene chloride, a polyvinyl chloride, and ethylene-vinyl acetate copolymer saponified material, on the side which does not form an electrode. Further, when the organic electroluminescent element is an active matrix organic electroluminescent element, it is necessary to use a TFT substrate provided with a thin film transistor (TFT) as a substrate.

  There are two methods for driving an organic electroluminescent device, a passive matrix method and an active matrix method. The organic electroluminescent device of the present invention is either a passive matrix organic electroluminescent device or an active matrix organic electroluminescent device. Applicable. The passive matrix method is a method in which stripe-shaped electrodes are opposed to each other so as to be orthogonal to each other with an organic light emitting layer interposed therebetween, and light is emitted at the intersection. This is a method of emitting light independently for each pixel by using a TFT) substrate. As the thin film transistor (TFT), an amorphous silicon or polysilicon thin film transistor (TFT) is used.

  In the passive matrix type organic electroluminescence device, the lighting time in each pixel becomes shorter as the number of stripe-shaped electrodes to be scanned becomes larger. Therefore, it is necessary to increase the instantaneous light emission luminance in the ON state. When the instantaneous light emission luminance is increased, the lifetime of the element is reduced, so that it is not suitable for a large-capacity display that requires hundreds to thousands of electrodes on the stripe to be scanned. On the other hand, each active matrix organic electroluminescent element is provided with a switching element and a memory element (active element) for each pixel, so that the operation state can be maintained for one scanning cycle. Even if the size is increased, the instantaneous luminance may be small and the durability is excellent. Moreover, it is advantageous for displaying moving images that require a high-speed response such as a display.

  The reflective electrode (21), which is the first electrode, can be formed as a positive electrode by using a metal material such as Mg, Al, or Cr by a vacuum film forming method such as a vapor deposition method or a sputtering method. Further, the reflective electrode may have a two-layer structure of a reflective electrode such as Mg, Al, and Cr and a transparent electrode such as ITO. At this time, ITO is provided as an anode interface layer.

  After forming the reflective electrode (21), a partition wall (22) is formed between the reflective electrodes so as to cover the edge of the reflective electrode. The partition wall needs to have insulating properties, and a photosensitive material or the like can be used. The photosensitive material may be a positive type or a negative type, and a novolac resin, a polyimide resin, or the like can be used, and a partition wall is formed through an exposure process and a development process by a photolithography method.

  A hole transport layer (22) is provided on the reflective electrode (21). As the hole transport layer forming material, poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (PEDOT / PSS) or the like can be used. PEDOT / PSS is dissolved in water to form a coating solution, which is coated on a substrate by a spin coating method or the like and dried.

  On the hole transport layer (22), organic light emitting layers (24a, 24b, 24c) are provided. When organic electroluminescent elements are displayed in full color, it is necessary to pattern organic light emitting layers having red (R), green (G), and B (blue) emission colors for each pixel, as shown in FIG. Has a red organic light emitting layer (24a), a green organic light emitting layer (24b), and a blue organic light emitting layer (25b). As the organic light emitting layer forming material, polyparaphenylene vinylene (PPV), polyfluorene (PF), or the like can be used. These organic light-emitting materials are dissolved in an aromatic organic solvent such as toluene to form ink, and are patterned into three colors by using a printing method.

  As a printing method, an ink jet printing method, an offset printing method, a letterpress printing method, or the like can be used, and among these, a letterpress reverse offset printing method can be preferably used. FIG. 8 shows a schematic diagram of the printing process in the letterpress reverse offset printing method.

In FIG. 8, a blanket (53) is mounted around a blanket cylinder (52) on the main body frame (51). Reference numeral (54) denotes a printing stage, which fixes the relief printing plate (59) and the substrate to be printed (56) during printing. Further, the printing stage (54) is movable in the uniaxial direction on the main body frame (51). In the figure, (57) is ink. A first electrode, a partition, and a hole transport layer are formed in advance on the substrate to be printed.

  The letterpress (59) is fixed on the printing stage (54), and the ink (57) is previously applied to the blanket (53) by an ink supply means (not shown) by a curtain coating method, a bar coating method, a wire coating method, a slit. It is applied using a coating such as a coating method (FIG. 8A). By moving the printing stage (54) and rotating the blanket cylinder, the ink film on the blanket (53) is removed by the relief pattern (59) which is the negative pattern of the desired pattern, and the ink on the blanket is changed to the desired pattern. Patterning is performed (FIG. 8B). Next, the printing stage (54) is moved and the blanket cylinder is rotated, whereby the ink pattern on the blanket is transferred onto the substrate (56) to be printed, and the printing process is completed (FIGS. 8C and 8D). )).

  5 is a system in which a blank cylinder is fixed and a stage including a relief plate and a substrate to be printed is moved, the relief reversal offset printing device of the present invention is a printing device. In some cases, the stage may be fixed and the bran cylinder may move.

  The printing blanket in the present invention is preferably composed of a material having a certain degree of flexibility such as a polymer film or rubber, and silicone rubber can be used for the blanket.

  Next, an electron injecting protective layer (25) is provided on the organic light emitting layers (24a, 24b, 24c). As a material for forming an electron injecting protective layer, rare earth elements having a low work function such as Ca and Ba can be used, and these rare earth elements are formed by vacuum deposition to form an electron injecting protective layer.

  Next, a transparent electrode (26) is provided as a cathode on the electron injecting protective layer (25). In forming the transparent electrode, the transparent conductive film forming method of the present invention shown above can be used. ITO can be suitably used as the transparent electrode forming material. In the top emission type organic electroluminescent device, the transparent conductive film forming method of the present invention can be suitably used when forming a transparent electrode. Since the transparent conductive film forming method of the present invention can reduce damage to an organic thin film such as an organic light emitting layer when forming a film by sputtering, an organic electroluminescent device having excellent light emitting characteristics can be obtained. . Moreover, the transparent conductive film forming method of the present invention can also suppress the temperature rise of the patterning mask during film formation. Therefore, thermal expansion and thermal deformation of the mask can be suppressed, and the transparent electrode can be accurately patterned. In addition, the organic electroluminescent element of this invention is good also considering a reflective electrode as a cathode and a transparent electrode as an anode.

  Next, a reflective electrode (21), a partition wall (22), a hole transport layer (23), an organic light emitting layer (24a, 24b, 24c), an electron injecting protective layer (25), and a transparent electrode (26) are formed. Sealing is performed on the substrate (20). First, a barrier layer (27) is formed on the entire substrate (20).

  As the barrier layer (27), a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, or the like can be used. The barrier film is formed by a CVD method. In the CVD method, a vaporized compound (source gas) containing the element to be filmed is mixed as it is or mixed with a carrier gas such as hydrogen or nitrogen, and is sent as uniformly as possible to the substrate surface heated at high temperature. In this method, a thin film is formed on a substrate by causing a chemical reaction such as reduction, oxidation, or substitution.

  Furthermore, the base material provided with the barrier layer (27) is bonded to the sealing substrate (29) through the resin layer (28). As a sealing substrate (29), what is necessary is just to have transparency, and glass and plastic materials, such as alkali free glass and alkali glass, can be used. As the resin layer (28), a photo-curing adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin made of an epoxy resin, an acrylic resin, a silicone resin, or the like, or ethylene ethyl acrylate (EEA) Examples thereof include acrylic resins such as polymers, vinyl resins such as ethylene vinyl acetate (EVA), thermoplastic resins such as polyamide and synthetic rubber, and thermoplastic adhesive resins such as acid-modified products of polyethylene and polypropylene.

  As a bonding method, a method by pressure bonding with a heated roll can be used. Moreover, when using a photocurable adhesive resin as a resin layer, it can bond together by irradiating with ultraviolet light.

  Moreover, in the organic electroluminescent element of this invention, it can be set as a flexible organic electroluminescent element by using a flexible plastic base material for a base material and a sealing base material.

  Moreover, in the organic electroluminescent element of this invention, it can be set as a transparent organic electroluminescent element by making both electrodes into a transparent electrode, making a base material into a transparent base material, and sealing by a transparent material. FIG. 6 is an explanatory sectional view of the transparent electroluminescent element. In FIG. 6, a transparent electrode (31) is formed as a first electrode on a transparent substrate (30). Further, as in FIG. 5, a partition wall (22), a hole transport layer (23), an organic light emitting layer ( 24a, 24b, 24c), an electron injecting protective layer (25), and a transparent electrode (26) are formed. Furthermore, it is sealed with a barrier layer (27), a resin layer (28), and a sealing substrate (29) having transparency. In the transparent organic electroluminescent element, it is possible to display images from both the substrate side and the opposite side of the substrate.

  A glass substrate was used as a substrate, Cr was formed on the substrate as a reflective electrode as an anode, and ITO was laminated as an anode interface layer by a sputtering method. The laminated film of Cr and ITO on the obtained substrate was patterned by a photolithography method to obtain a stripe pattern. Next, a partition wall was formed by a photolithography method using a polyimide material so as to cover the end portion of the striped Cr. Next, PEDOT / PSS was used as a hole transport material, which was dissolved in water to form a coating solution, and a hole transport layer was formed by a spin coating method.

  Next, using a green organic light emitting material made of polyfluorene (PF), this green organic light emitting material was dissolved in toluene to form an ink, and an organic light emitting layer was formed in stripes by letterpress reverse printing. Next, Ca and Al were formed in this order on the organic light emitting layer by a vapor deposition method by a vacuum vapor deposition method. At this time, the electron injecting protective layer made of Ca and Al was formed using a mask so as to be orthogonal to the Cr stripe pattern of the anode.

Next, a transparent electrode was formed using the transparent conductive film forming method of the present invention. As the sputtering apparatus, a DC magnetron sputtering apparatus was used. At this time, in the RF magnetron sputtering apparatus, a grid with a magnet was provided between the substrate and the target, the magnet on the grid was rod-shaped, and the magnets arranged radially were the center. Were arranged to be N poles. A mask was provided so as to come into contact with the substrate, and the mask was fixed by a magnet folder. A Peltier element was provided on the opposite side of the substrate from the transparent electrode film formation surface. The sputtering conditions are a gas pressure of 0.5 Pa, a gas flow rate of Ar / O ₂ = 100 / 1.0, a discharge power of 0.6 kW, and a target-substrate distance of 130 mm. At this time, ITO as a transparent electrode was provided so as to have a thickness of 150 cm so as to be perpendicular to the stripe pattern of Cr as a reflective electrode so as to overlap the electron injecting protective layer. The mask temperature during sputtering film formation was 50 ° C.

  Next, a silicon oxide film is provided over the entire light emitting region of the organic electroluminescent element by a CVD method, and further sealed by bonding to a glass substrate via an epoxy-based adhesive, to form a top emission type organic electroluminescent element. Obtained.

Regarding the device characteristics of the obtained organic electroluminescence device, the maximum luminance was 2000 cdm ⁻² and the maximum current efficiency was 2.2 cdA ⁻¹ .

(Comparative example)
As in the example, a transparent electrode was formed on a glass substrate on which a reflective electrode, a partition wall, a hole transport layer, an organic light emitting layer, and an electron injecting protective layer were formed using a DC magnetron sputtering apparatus in the same manner as in the example. I did it. However, in the DC magnetron sputtering apparatus, no magnet was provided on the grid. Furthermore, no Peltier element was provided on the substrate. In the sputtering, other sputtering conditions are the same as those in the examples.

At this time, the mask temperature during sputtering was 60 ° C., which was higher by about 10 ° C. than Example 1. Moreover, sealing was performed on the substrate on which the transparent electrode was formed in the same manner as in the example to obtain an organic electroluminescent element. The maximum luminance of the obtained organic electroluminescent element was 200 cdm ⁻¹ and the maximum current efficiency was 0.05 cdA ⁻¹ .

FIG. 1 is a schematic view of a DC magnetron sputtering apparatus used for forming a transparent conductive film of the present invention. FIG. 2 is an example of a layout diagram of magnets on the grid. FIG. 3 shows a magnet loading jig for bundling the bar magnets of the present invention. FIG. 4 is an explanatory view of the periphery of the substrate in the transparent conductive film forming method of the present invention. FIG. 5 is an explanatory sectional view of the Peltier element. FIG. 6 is an explanatory sectional view of a top emission type organic electroluminescent element. FIG. 7 is an explanatory cross-sectional view of a transparent electroluminescent element. FIG. 8 is a schematic diagram of a printing process by the letterpress reverse offset printing method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Grid 3 Target 4 Packing plate 5 Cathode magnet 6 Magnet loading jig 7 Magnet 8 Magnetic field line (repulsive magnetic field)
9 Plasma 10 Ar ion 11 Secondary electron 12 Ground 13 Peltier element 14 Magnet folder 15 Mask 15a Mask opening 16 Mask frame 20 Base material 21 Reflecting electrode (first electrode)
22 partition wall 23 hole transport layer 24a red (R) organic light emitting layer 24b green (G) organic light emitting layer 24c blue (B) organic light emitting layer 25 electron injecting protective layer 26 transparent electrode (second electrode)
27 barrier layer 28 resin layer 29 sealing substrate 30 transparent substrate 31 transparent electrode 41 lead wire 42 ceramic substrate 43 metal electrode 44a p-type semiconductor 44b n-type semiconductor 51 body frame 52 blank cylinder 53 blanket 54 printing stage 55 intaglio 56 covered Transfer substrate 57 Ink 58 Doctor blade 59 Letterpress L Light emission

Claims (6)

In a transparent conductive film forming method in which a mask is provided on a substrate and a transparent conductive film is patterned on the substrate by a sputtering method, a grid including a magnet is provided between the target and the substrate, the magnet is rod-shaped, and the magnet is A transparent conductive made of a target-forming material on the substrate by sputtering, by arranging a plurality of radial lines on the grid, making the polarity of the magnet coincide with the center direction of the grid, applying a voltage to the grid, and sputtering. A method for forming a transparent conductive film, comprising patterning a film. 2. The transparent conductive material according to claim 1 , wherein the plurality of bar-shaped magnets are loaded into a cavity of a magnet loading jig in which a cavity is formed in a non-magnetic material, and the magnet loading jig is provided on a grid. Film forming method. During forming a transparent conductive film, a transparent conductive film forming method according to claim 1 or 2, wherein the substrate is cooled by the Peltier element. In the method of manufacturing an organic electroluminescent element, the first electrode, the organic light emitting layer, and the second electrode are provided on the base material at least in this order, and the organic light emitting layer emits light by passing a current between the electrodes. method of manufacturing an organic electroluminescent device which is characterized in that the pattern formed by the method according to at least one of any of claims 1 to 3 electrodes. In the method of manufacturing a top emission type organic electroluminescence device, a transparent electrode is provided in a manufacturing method of a top emission type organic electroluminescence device comprising a reflective electrode, an organic light emitting layer, and a transparent electrode on a substrate in this order, and causing the organic light emitting layer to emit light by passing a current between the electrodes A method for producing a top emission type organic electroluminescence device, which is formed by the method according to any one of 1 to 3 . In the manufacturing method of the organic electroluminescent element of Claim 4 or Claim 5 , the said organic light emitting layer forming material is melt | dissolved or disperse | distributed to a solvent, and it is set as the ink by a relief printing offset printing method using this ink. The manufacturing method of the organic electroluminescent element characterized by including the process of forming an organic light emitting layer on a base material.

Images