WO2013114552A1 - Organic electroluminescence panel and method for manufacturing same - Google Patents

Abstract

An organic EL panel having a substrate, and having at least one organic functional layer, which is arranged between a first electrode layer and a second electrode layer facing each other on the substrate and which demarcates a light emission area, formed by the scanning of a droplet discharge nozzle. The organic functional layer comprises a plurality of band-shaped organic layers which are arranged in a row on the substrate and which have edge sections that are bonded to each other. The edge sections of the band-shaped organic layers are on a normal plane of the substrate including a center straight line passing through the planar center of the light emission area and one of two parallel lines that are parallel to the center straight line and that are positioned equidistant from the planar center of the light emission area.

Description

Organic electroluminescence panel and manufacturing method thereof

The present invention relates to an organic EL panel having an organic electroluminescence (hereinafter referred to as organic EL) material as a light emitting layer and a method for manufacturing the same.

An organic EL panel is a surface light emitter in which a plurality of organic functional layers made of an organic compound having a charge transport property are sandwiched between an anode and a cathode, and at least one light emitting layer is included in the organic functional layer.

Organic EL panels have been put into practical use as display devices such as mobile phones, and are being applied to lighting fixtures as thin surface light sources.

As a method for forming an organic functional layer when manufacturing an organic EL panel, a coating method (inkjet method) by scanning a droplet discharge nozzle is known. In the ink jet method, a liquid containing an organic material is ejected through a nozzle in the form of a micro flow (jet flow or drop flow) to deposit droplets on the anode, and then dried to obtain a hole injection layer, a positive Organic functional layers such as a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are formed and stacked.

Conventionally, in an organic EL display device manufactured using an ink jet method, light emission unevenness has occurred at a boundary portion between coating layers of an organic EL material applied by a plurality of scans in the image display area. The uneven light emission at the boundary part deteriorates the “look” of the screen of the organic EL display device that the observer gazes at. In view of this, various ink jet methods have been proposed in which the boundary portion that is an obstacle, that is, the joint portion of the coating layer, is made uniform to make it difficult to visually recognize light emission unevenness (see Patent Documents 1 to 6).

Even when the inkjet method used in the manufacture of a conventional organic EL display device is applied to the manufacture of an organic EL panel for a surface light source, the boundary portion becomes inconspicuous if a plurality of inkjet heads are arranged and scanned simultaneously. However, the use of a plurality of ink jet heads causes an increase in cost and size of manufacturing equipment. There is also a method to increase the width of the inkjet head by increasing the size, but currently there are many 3 to 7 cm wide inkjet heads available, and the wide and large heads are custom-made, making the head expensive and manufactured. Cost increases. Even with the conventional ink jet method, it is difficult to completely eliminate the seam portion, and it is difficult to suppress the non-uniformity of the light emitting surface due to uneven light emission of the seam by suppressing the increase in the manufacturing cost of the organic EL panel for the surface light source. .

JP 2004-327241 A JP 2006-68598 A JP 2008-249781 A JP 2009-66526 A JP 2011-54386 A JP 2006-7079 A

The present invention has been made in view of the above points, and provides an organic EL panel in which nonuniformity of a light emitting surface due to light emission unevenness of a joint of a coating layer generated by an ink jet method is suppressed, and a method for manufacturing the same. An example of the problem.

In the organic EL panel of the present invention, at least one organic functional layer that is disposed on the substrate and between the first electrode layer and the second electrode layer facing each other in the normal direction of the substrate to define a light emitting area is a liquid. An organic EL panel formed by scanning a droplet discharge nozzle,
The organic functional layer is composed of a plurality of band-like organic layers juxtaposed on the substrate and the edges are joined to each other, and the edge of the band-like organic layer passes through the center of the plane of the light emitting area and the center line , And in the normal plane of the substrate including one of two parallel lines separated by an equal distance from the center of the surface of the light emitting area.

Further, the organic EL panel manufacturing method of the present invention includes at least one layer disposed on the substrate and between the first electrode layer and the second electrode layer facing each other in the normal direction of the substrate to define a light emitting area. A method of manufacturing an organic EL panel in which an organic functional layer is formed by scanning a droplet discharge nozzle,
The first electrode layer is scanned side by side with a droplet discharge nozzle that moves on a plurality of parallel paths at equal intervals along the surface of the first electrode layer. Including a scanning step of applying a plurality of band-like organic layers bonded to each other
In the scanning step, the droplet discharge nozzle is separated from the center straight line through which the edge of the band-shaped organic layer passes the center of the surface of the light emitting area, and is parallel to the center straight line by an equal distance from the surface center of the light emitting area. The position is controlled relative to the substrate so as to be in the normal plane of the substrate including any one of two parallel lines.

Effects of the present invention

According to the organic EL panel of the present invention, for example, the generation of an irregular or unbalanced pattern due to the presence of a seam in the light emitting surface is suppressed. The feeling of strangeness can be suppressed.

It is a top perspective view which shows the structure of the organic electroluminescent panel of embodiment of this invention. FIG. 2 is a partial cross-sectional view taken along line AA in FIG. 1. It is sectional drawing which shows the board | substrate in the manufacture process of an organic electroluminescent panel, and the structure formed on it. It is sectional drawing which shows the board | substrate in the manufacture process of an organic electroluminescent panel, and the structure formed on it. It is sectional drawing which shows the board | substrate in the manufacture process of an organic electroluminescent panel, and the structure formed on it. It is sectional drawing which shows the board | substrate in the manufacture process of an organic electroluminescent panel, and the structure formed on it. It is sectional drawing which shows the board | substrate in the manufacture process of an organic electroluminescent panel, and the structure formed on it. It is a schematic perspective view which shows the structure of the inkjet coating device used when forming a strip | belt-shaped organic layer with the inkjet method. It is a perspective view which shows an example of the movement form of the inkjet head which moves on the surface of a board | substrate. It is a top perspective view which shows the structure of the organic electroluminescent panel of other embodiment of this invention. It is a top perspective view which shows the structure of the organic electroluminescent panel of other embodiment of this invention. It is a top perspective view which shows the structure of the organic electroluminescent panel of other embodiment of this invention. It is a top perspective view which shows the structure of the organic electroluminescent panel of other embodiment of this invention. It is a top perspective view which shows the structure of the organic electroluminescent panel of other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a portion of an organic EL panel according to an embodiment of the present invention as viewed from the upper surface side on the cathode side, and FIG. 2 is a partial cross-sectional view of the organic EL panel taken along line AA in FIG. It is sectional drawing.

In the present embodiment, as shown in FIG. 2, a transparent anode 2 (first electrode layer) formed on a flat substrate 1 or a film-like transparent substrate 1 made of glass, resin, or the like, and laminated thereon. This is an organic EL panel having an organic EL laminate OEL including a light emitting layer 5 and a cathode 9 (second electrode layer) laminated thereon. The organic EL laminate OEL is formed by laminating an organic functional layer composed of a plurality of connected organic organic layers OG formed by an inkjet method, and the hole injection layer 3 / hole transport layer is formed as an organic functional layer. 4 / light emitting layer 5 / hole blocking layer 6 / electron transport layer 7 / electron injection layer 8 1 and 2, a transparent anode 2 extending in the XY direction on the panel plane is formed on a substrate 1. A solid film-like cathode 9 is formed on the electron injection layer 8 of the organic EL laminate OEL. Note that it is not necessary to form all the organic functional layers of the organic EL panel by the ink jet method, and the film can be formed by another wet method or a vapor deposition method. For example, the hole injection layer and the hole transport layer may be uniformly formed as a solid film by a spray method or the like. For example, the hole blocking layer, the electron transport layer, and the electron injection layer cathode may be uniformly and sequentially formed as a solid film by an evaporation method or the like. Film formation by an ink jet method is preferable for at least a light emitting layer having a large influence on light emission unevenness.

As shown in FIG. 2, each organic functional layer of the organic EL laminate OEL is composed of a plurality of strip-like organic layers OG that are juxtaposed in parallel in the longitudinal direction (X direction) and joined to each other. The edges of adjacent ones of the band-shaped organic layers OG are seams SM that are in contact with each other.

The joint SM of each organic functional layer of the organic EL laminate OEL is in the normal plane of the substrate including the central straight line passing through the surface center of the light emitting area of the organic EL panel, and is parallel to the central straight line and equal to the surface center of the light emitting area. It exists in the normal plane of the substrate including two parallel lines separated by (W). That is, the joint SM of each organic functional layer of the organic EL stacked body OEL exists symmetrically with respect to a straight line passing through the center of the surface of the light emitting area. Here, the light emitting area of the organic EL panel is a portion where the anode 2 and the cathode 9 sandwich the organic EL laminated body OEL indicated by oblique lines in FIG. The surface center of the light emitting area is the center of gravity of the shape of the light emitting area when the organic EL panel is viewed in plan from the anode 2 or the cathode 9 side. For example, when the light emitting area shown in FIG. 2 is rectangular, the point where the diagonal lines intersect is the surface center of the light emitting area.

According to the present embodiment, the joint portion formed by the scanning in which the inkjet head moves along each parallel path on the surface is arranged at a position that is symmetric with respect to the center of the light emitting area, thereby causing unevenness due to the joint portion. Even so, it is possible to reduce discomfort for humans who see the organic EL panel, and therefore, it is possible to reduce the deterioration factor of the “look” of the organic EL panel.

The process for manufacturing the organic EL panel will be described with reference to FIGS.

As shown in FIG. 3, a parallel plate substrate 1 such as cleaned glass is prepared, and an anode 2 such as ITO is formed on the substrate 1 by sputtering or photolithography.

Then, as shown in FIG. 4, a droplet Lq of a solution of the material constituting the hole injection layer of the organic functional layer is supplied onto the anode 2 from a droplet discharge nozzle (not shown) of the inkjet head 12. The In the inkjet coating process, the inkjet head 12 applies the strip-shaped organic layer OG on the anode 2 while scanning in parallel with the X direction (scanning direction) in order to extend the organic layer. After one scanning application, the inkjet head is transferred in the Y direction at the end of the substrate 1 and sequentially applied at adjacent positions. Edges of adjacent coated organic strips OG (extending in the scanning direction) are brought into contact with each other, and a joint SM is formed on the anode 2.

Thereafter, the organic layer is subjected to drying treatment, and as shown in FIG. 5, the hole injection layer 3 in which the edges of the band-shaped organic layer OG are connected by the joint SM is formed.

Then, a combination of the inkjet coating process and the drying process is sequentially repeated for each organic functional layer that performs the respective functions, and as shown in FIG. 6, a multilayer organic EL in which the edges of each band-shaped organic layer are connected by a joint SM. A laminated body OEL (hole injection layer 3 / hole transport layer 4 / light emitting layer 5 / hole blocking layer 6 / electron transport layer 7 / electron injection layer 8) is formed.

Then, as shown in FIG. 7, after the organic EL laminate OEL is formed, a metal film cathode 9 is formed by vapor deposition or the like. Here, a portion where the anode 2 and the cathode 9 sandwich the organic EL laminate OEL shown in FIG. 1 defines a light emitting area of the organic EL panel.

Thereafter, a sealed organic EL panel can be obtained through a sealing process.

FIG. 8 is a schematic perspective view showing the configuration of an ink jet coating apparatus that coats a strip organic layer in the ink jet coating process.

As shown in FIG. 8, the inkjet coating apparatus includes a stage 10 that fixes the substrate 1, a stage moving mechanism 11 that moves the stage 10 in the Y direction, the inkjet head 12, and the inkjet head 12 in the X direction orthogonal to the Y direction. A head moving mechanism 13 for moving is provided. The ink jet coating apparatus also includes a control unit (not shown) that drives the stage moving mechanism 11, the ink jet head 12, and the head moving mechanism 13. The inkjet head 12 is provided with a plurality of droplet discharge nozzles (not shown) for discharging droplets containing an organic material as a raw material such as the hole injection layer 3 toward the surface of the substrate 1. . The control unit controls the movement of the stage moving mechanism 11 and the head moving mechanism 13 to move the inkjet head 12 in the Y direction and the X direction in the space above the substrate 1 fixed to the stage 10. Further, the control unit controls the ejection of droplets with respect to the inkjet head 12. The viscosity of the droplet containing the organic material ejected by the inkjet head 12 is 2 to 5 cp, and the surface tension is 30 to 40 mN / m. Moreover, the boiling point of this organic material is larger than 200 degreeC. Furthermore, the droplet discharge speed by the inkjet head 12 is, for example, about 4 m / sec, the discharge amount is about 15 ml, and the drive frequency is about 5 to 12 kHz. The moving speed of the inkjet head 12 is about 100 mm / sec.

As the inkjet head 12, an on-demand piezo type composed of a plurality of piezo elements can be used. Each solution tank (not shown) corresponding to each organic functional layer is connected to the inkjet head. For example, each of a plurality of droplet discharge nozzles in an inkjet head is formed with a piezo element having a solution chamber having a piezoelectric ceramic wall communicating with the nozzle. Pressure is applied to the solution by expansion and contraction of the solution chamber in accordance with the applied voltage to each piezo element, and the solution filled in each solution chamber is discharged from a plurality of nozzles (not shown) of the piezo element. As shown in FIG. 9, for example, according to the inkjet head 12 provided with several rows of several hundred nozzles arranged in the Y direction in parallel, a plurality of droplets Lq of the solution are as many as the number of nozzles arranged in the Y direction. The strip-shaped organic layer OG can be applied on the anode 2 with a width (W _OG ).

The ink jet head 12 controlled by the control unit is moved to one end Q1 of the substrate 1 shown in FIG. 9 and moved from the position toward the other end Q2 of the substrate 1 in the X direction. The ejection of droplets by the head 12 is executed. As a result, droplets of organic material discharged from the inkjet head 12 adhere to the area scanned by the inkjet head 12. At this time, droplets of the organic material are applied only to the region on the anode 2 (under the Q1-Q2 path).

When the ink jet head 12 reaches a position outside the end portion Q2 of the substrate 1 shown in FIG. 9, the ejection of the liquid droplets is stopped, and the ink jet head 12 moves relative to the substrate 1 in the Y direction toward the end portion Q3 of the substrate 1. The position Q3 shown in FIG. 9 is reached. Then, the inkjet head 12 again causes the inkjet head 12 to discharge the droplet Lq while moving from the position of the end Q3 of the substrate 1 toward the end Q4 of the substrate 1 in the X direction. This deposits organic material droplets only in the region on the adjacent anode 2 (under the Q3-Q4 path).

In this way, while ejecting droplets by the inkjet head 12, by moving the inkjet head 12 along the X direction and scanning the surface, the edges of the applied adjacent organic organic layers OG are brought into contact with each other. A joint SM is formed.

As described above, in the method of manufacturing the organic EL panel according to the embodiment, in the scanning process, the inkjet head 12 has the center (the center of gravity of the figure formed by the line connecting the plurality of droplet discharge nozzles) of the light emitting area. Passes through the center of the surface, or the edges of the ink-jet head 12 (the most ends of a plurality of droplet discharge nozzles in the direction perpendicular to the scanning direction) are applied and the edges of adjacent organic layers OG are in contact with each other Thus, the position is controlled relative to the substrate 1 so as to form the connecting joint SM. In other words, the inkjet head 12 (droplet discharge nozzle) has the edges of the adjacent strip-shaped organic layers applied on the center straight line passing through the center of the surface of the light emitting area and parallel to the center straight line and equal from the surface center of the light emitting area. Position control is performed relative to the substrate 1 so as to form a seam that contacts and connects on two parallel lines separated by a distance.

Furthermore, as shown in FIG. 7, the organic functional layer (hole injection layer 3 / hole transport layer 4 / light emitting layer 5 / hole blocking layer 6 / electron transport layer 7) corresponding to the step of applying the strip organic layer OG is applied. In each of the scanning steps shown in FIG. 4, the inkjet head 12 (droplet discharge nozzle) repeats for each electron injection layer 8) and the substrate 1 so that all the joints SM exist in the normal plane of the substrate 1. Relative to the position.

Moreover, in the said embodiment, although the light emitting layer 5 which consists of the mixed organic EL material can be made into one layer, the organic electroluminescent panel of monochromatic light emission, such as white, red, green, blue, can be produced, In addition to this, it consists of a multilayer light emitting layer. An organic EL panel can be produced. For example, a red light emitting layer, a green light emitting layer, and a blue light emitting layer are sequentially laminated to produce a white light emitting organic EL panel including three light emitting layers. In addition, a white-light-emitting organic EL panel including two light-emitting layers can be manufactured by sequentially stacking a yellow-orange light-emitting layer and a blue light-emitting layer.

Therefore, according to the present embodiment, the seam resulting from the scanning of the ink jet head for applying the organic EL material can be arranged symmetrically about the surface center of the light emitting area of the organic EL panel. Reminds the user of geometric regularity and improves the comfort of the viewer for the joint. In addition, since the number of heads mounted on the ink jet coating apparatus can be reduced, apparatus cost and apparatus size can be reduced. In addition, an ink jet head that can be obtained at present can be used, and it is possible to provide an organic EL panel that can suppress an unnecessary cost increase such as a custom head.

Furthermore, FIG. 10 shows the structure of an organic EL panel according to another embodiment of the present invention. This organic EL panel includes one seam SM in which the edges of adjacent organic layers OG adjacent to each other are in contact with each other along a central straight line passing through the center of the surface of the light emitting area. Are the same. FIG. 11 shows the structure of an organic EL panel according to still another embodiment of the present invention. In this organic EL panel, there is no joint where the edges of adjacent organic layers OG adjacent to each other are in contact with each other on the central straight line passing through the center of the surface of the light emitting area. 1 except that the seam SM is provided along two parallel lines that are separated by an equal distance (W) from the center of the surface. Thus, the joint SM of the organic EL panel only needs to exist along any straight line on the straight line in the plane of the light emitting area and on a parallel line separated by an equal distance from the center of the surface of the light emitting area.

12A and 12B show the structure of an organic EL panel according to another embodiment of the present invention. This organic EL panel is the same as the embodiment of FIGS. 10 and 11 except that the light emitting area (the portion where the anode 2 and the circular cathode 9 sandwiching the organic EL laminate OEL overlap) is circular. The surface center of the circular light emitting area is the surface center of the light emitting area when the organic EL panel is viewed from the anode 2 or the cathode 9 side. The center of the surface of the light emitting area may be the center of gravity of the shape of the light emitting area when the organic EL panel is viewed from the anode 2 or the cathode 9 side, and the light emitting area can be formed in various shapes such as a circle, a rectangle, and a polygon. is there.

Further, in the organic EL panel of the above embodiment, the organic EL laminated body OEL including a single layer of the solid film-like light emitting layer 5 is formed, but the light emitting layer is not limited thereto. For example, in the organic EL panel of another embodiment, as shown in FIG. 13, the light emitting layer is connected in contact with the edge of the adjacent organic organic layer OG on a central straight line passing through the center of the surface of the light emitting area. A set of a red light emitting layer R, a green light emitting layer G, and a blue light emitting layer B, which are juxtaposed in stripes in parallel with one seam SM and separated by a bank, can be sequentially arranged. The organic EL panel of this embodiment is the same as the embodiment of FIG. 10 except for the light emitting layer.

Furthermore, in the organic EL panel according to another embodiment, as shown in FIG. 14, the light emitting layer includes red light emitting layers R, green arranged side by side in stripes in the vertical direction with respect to the joint SM and separated by banks. A set of a light emitting layer G and a blue light emitting layer B can be sequentially arranged. The organic EL panel of this embodiment is the same as the embodiment of FIG. 10 except for the light emitting layer.

In the case of the embodiment shown in FIGS. 13 and 14, in the scanning step shown in FIG. 4, the droplet discharge nozzles of the inkjet head 12 individually collect droplets of light emitting materials of at least two colors corresponding to the respective light emitting color light emitting layers. A plurality of sets of nozzles are used so as to discharge the ink. Furthermore, the inkjet head 12 is controlled so that the strip-shaped organic layer OG is coated in the number of stripe shapes corresponding to the light emitting material on the anode 2 (first electrode layer).

An example of the organic EL panel of the present embodiment is, as shown in FIG. 2, an anode 2 / hole injection layer 3 / hole transport layer 4 / light emitting layer that are sequentially laminated on a transparent substrate 1 such as glass. 5 / hole blocking layer 6 / electron transport layer 7 / electron injection layer 8 / cathode 9 /. In addition to this laminated structure, although not shown, an anode 2 / hole injection layer 3 / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / hole transport layer 4 and hole blocking layer 6 are provided. Although omitted, and not shown, the anode 2 / hole transport layer 4 / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / hole injection layer 3 and hole blocking layer 6 are omitted. Although not shown in the figure, the anode 2, the light emitting layer 5, the electron transport layer 7, the electron injection layer 8, the cathode 9 / the hole injection layer 3, the hole transport layer 4, and the hole blocking layer 6 may be omitted. It is included in the present invention. Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. In any case, the present invention is not limited to these laminated structures, and a laminated structure including at least a light-emitting layer or a charge transport layer that can also be used is also included in the invention.

[substrate]
As the substrate 1, a quartz or glass plate, a metal plate or a metal foil, a resin substrate to be bent, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic EL panel may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

[Anode and cathode]
The anode 2 that supplies holes to the layers up to the light emitting layer is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, or a metal such as indium and / or tin or zinc oxide (ITO or IZO). It is composed of an oxide, a metal halide such as copper iodide, carbon black, or a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

The anode is usually formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode can also be formed by dispersing and coating the substrate. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate by electrolytic polymerization, or the anode can be formed by applying a conductive polymer on the substrate.

The anode usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

The thickness of the anode depends on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. If it may be opaque, the thickness of the anode is arbitrary, and the anode may be integrated with the substrate 1. Furthermore, different conductive materials may be laminated.

The surface of the anode is treated with ultraviolet (UV) / ozone, oxygen plasma, or argon plasma for the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection. Is preferred.

As a material of the cathode 9 for supplying electrons to the layers up to the light emitting layer, a material used for the anode can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. A suitable metal such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In addition, only 1 type may be used for the material of the cathode 9, and 2 or more types may be used together by arbitrary combinations and a ratio. The thickness of the cathode is usually the same as that of the anode.

Further, for the purpose of protecting the cathode made of a low work function metal, it is preferable to further laminate a metal layer having a high work function and stable to the atmosphere because the stability of the organic EL panel is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Furthermore, when the anode and cathode are on the light emission extraction side (first electrode layer), the material and film thickness are selected so as to be transparent or translucent. In particular, it is preferable to select a material in which either one or both of the anode and the cathode has a transmittance of at least 10% at the emission wavelength obtained from the organic light emitting material.

[Organic functional layer]
* Hole injection layer *
The hole injection layer 3 is preferably a layer containing an electron accepting compound.

The film thickness of the hole injection layer is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. The hole injection layer is preferably formed by a wet film formation method such as an inkjet method from the viewpoint of reducing dark spots.

When forming a hole injection layer by a wet film formation method, the material for forming the hole injection layer is usually mixed with an appropriate solvent (a solvent for the hole injection layer) to form a composition for film formation (hole An injection layer forming composition) is prepared, and this hole injection layer forming composition is coated on the anode by an appropriate technique to form a film and dried to form a hole injection layer.

The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as a constituent material of the hole injection layer. Examples of the solvent include, but are not limited to, ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether acetate (PGMEA), 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2 -Aromatic toluene such as methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and the like.

Examples of ester solvents include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.

Examples of the amide solvent include N, N-dimethylformamide and N, N-dimethylacetamide. In addition, dimethyl sulfoxide and the like can also be used. These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

As long as the hole transporting compound is a compound having a hole transporting property that is usually used in a hole injection layer of an organic EL panel, a polymer or the like may be a monomer or the like. Although it may be a low molecular compound, it is preferably a low molecular compound.

The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode to the hole injection layer. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives typified by phthalocyanine copper (CuPc), porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, and tertiary amines linked by fluorene groups. Examples thereof include compounds, hydrazone derivatives, silazane derivatives, silanamine derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, and carbon.

Here, the derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a body.

The hole transporting compound used as the material for the hole injection layer may contain any one of these compounds alone, or may contain two or more. In the case of containing two or more kinds of hole transporting compounds, the combination is arbitrary, but one or more kinds of aromatic tertiary amine polymer compounds and one or two kinds of other hole transporting compounds. The above can also be used together. From the viewpoints of amorphousness and visible light transmittance, an aromatic amine compound is preferable for the hole injection layer, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine. Specific examples include those described in the pamphlet of International Publication No. 2005/089024.

As the hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene, which is a derivative of polythiophene, in high molecular weight polystyrene sulfonic acid is also preferable. Moreover, the end of this polymer may be capped with methacrylate or the like.

The concentration of the hole transporting compound in the composition for forming a hole injection layer is usually 0.01% by weight or more, preferably 0.1% by weight or more, and more preferably 0.00% by weight in terms of film thickness uniformity. 5% by weight or more, usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

The composition for forming a hole injection layer preferably contains an electron-accepting compound, and may further contain other components in addition to the hole-transporting compound and the electron-accepting compound. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and ratios.

* Hole transport layer *
The material of the hole transport layer 4 may be any material that has been conventionally used as a constituent material of the hole transport layer. For example, the hole transport layer is exemplified as the hole transport compound used in the above-described hole injection layer. Things. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatics Group derivatives, metal complexes and the like. Also, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having branches in the main chain and having three or more terminal edges, or a so-called dendrimer.

Specific examples of the material for the hole transport layer 4 include polyarylene derivatives described in JP-A-2008-98619.

When the hole transport layer is formed by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer, followed by drying after the wet film formation.

In addition to the hole transporting compound, the hole transporting layer forming composition contains a solvent. The solvent used is the same as that used for the composition for forming the hole injection layer. The film forming conditions, the drying conditions, and the like are the same as in the case of forming the hole injection layer.

The hole transport layer may contain various light emitting materials, electron transport compounds, binder resins, coatability improvers and the like in addition to the hole transport compound.

The film thickness of the hole transport layer is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

The hole transport layer may be formed by a vacuum deposition method or a wet film formation method, but is preferably formed by a wet film formation method from the viewpoint of reducing dark spots.

The hole transport layer 4 may be a layer containing a polymer obtained by crosslinking an amine-based crosslinking compound.

* Light emitting layer *
The light emitting layer 5 contains at least a material having a light emitting property (light emitting material) as a constituent material, and preferably a compound having a hole transporting property (hole transporting compound) or an electron transport. A compound (electron transporting compound) having the following properties: A light emitting material may be used as a dopant material, and a hole transporting compound, an electron transporting compound, or the like may be used as a host material. There is no particular limitation on the light-emitting material, and a material that emits light at a desired light emission wavelength and has favorable light emission efficiency may be used. In addition, when forming a light emitting layer with a wet film-forming method, it is preferable to use a low molecular weight material in any case.

Any known material can be applied as the light emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferred from the viewpoint of internal quantum efficiency. Alternatively, blue may be used in combination, such as using a fluorescent material, and green and red using a phosphorescent material.

For the purpose of improving the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecule of the luminescent material, or to introduce a lipophilic substituent such as an alkyl group.

Examples of fluorescent light emitting materials (blue fluorescent dyes) that emit blue light include naphthalene, perylene, pyrene, chrysene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof.

Examples of the fluorescent light-emitting material (green fluorescent dye) that emits green light include aluminum complexes such as quinacridone derivatives, coumarin derivatives, and Alq3 (tris (8-hydroxy-quinoline) aluminum).

Examples of the fluorescent light emitting material (yellow fluorescent dye) that emits yellow light include rubrene and perimidone derivatives.

Examples of fluorescent materials that emit red light (red fluorescent dyes) include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, Examples include benzothioxanthene derivatives and azabenzothioxanthene.

As the phosphorescent material, for example, a long-period type periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to a long-period type periodic table) selected from Group 7 to 11 And an organometallic complex containing a metal. Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. As the ligand of the complex, a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or a (hetero) arylpyrazole ligand and a pyridine, pyrazole, phenanthroline, or the like is connected is preferable. A pyridine ligand and a phenylpyrazole ligand are preferable. Here, (hetero) aryl represents an aryl group or a heteroaryl group.

Specific examples of phosphorescent materials include tris (2-phenylpyridine) iridium (Ir (ppy) 3), tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, and bis (2-phenylpyridine). ) Platinum, tris (2-phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethylplatinum porphyrin, octaphenylplatinum porphyrin, octaethylpalladium porphyrin, octaphenylpalladium porphyrin, and the like.

The molecular weight of the compound used as the light emitting material is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more, still more preferably. The range is 400 or more. If the molecular weight of the luminescent material is too small, the heat resistance will be significantly reduced, gas generation will be caused, the film quality will be reduced when the film is formed, or the morphology of the organic functional layer will be changed due to migration, etc. There is a case. On the other hand, if the molecular weight of the luminescent material is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

In addition, any 1 type may be used for a luminescent material, and 2 or more types may be used together by arbitrary combinations and a ratio. The ratio of the light emitting material in the light emitting layer is usually 0.05% by weight or more and usually 35% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range. The component having the highest content in the light emitting layer is called a host material, and the component having a smaller content is called a guest material. Therefore, at least two kinds of solid contents (host material and guest material) to be the light emitting layer can be prepared by being dispersed or dissolved in a solvent as a solute in the light emitting layer coating liquid.

The light emitting layer may contain a hole transporting compound as a constituent material. Here, among the hole transporting compounds, examples of the low molecular weight hole transporting compound include various compounds exemplified as the hole transporting compound in the hole injection layer 3 described above, for example, Two or more condensed aromatic rings containing two or more tertiary amines represented by 4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) are attached to the nitrogen atom. Aromatic amine compounds having a starburst structure (Journal 芳香 of ジ ア ミ ン Luminescence, such as substituted aromatic diamines (Japanese Patent Laid-open No. Hei 5-234681), 4,4 ', 4 "-tris (1-naphthylphenylamino) triphenylamine) 1997, Vol.72-74, pp.985), aromatic amine compounds consisting of tetramers of triphenylamine (Chemical Communications, 1996, pp.2175), 2,2 ′, 7,7′-tetrakis- ( Diphenylamino) -9, '- spiro compounds such spirobifluorene (Synthetic Metals, 1997, Vol.91, pp.209) and the like.

In addition, in a light emitting layer, only 1 type may be used for a hole transportable compound, and it may use 2 or more types together by arbitrary combinations and a ratio.

The proportion of the hole transporting compound in the light emitting layer is usually 0.1% by weight or more and usually 65% by weight or less. If the amount of the hole transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of hole transportable compounds, it is made for the total content of these to be contained in the said range.

The light emitting layer may contain an electron transporting compound as a constituent material. Here, among the electron transporting compounds, examples of low molecular weight electron transporting compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5, -Bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7 Diphenyl-1,10-phenanthroline (BCP, bathocuproin), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4 , 4′-bis (9H-carbazol-9-yl) biphenyl (CBP), etc. In the light emitting layer, only one kind of electron transporting compound may be used, or two or more kinds may be used. It may be used in combination with combination and ratio.

The proportion of the electron transporting compound in the light emitting layer is usually 0.1% by weight or more and usually 65% by weight or less. If the amount of the electron transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of electron transport compounds, it is made for the total content of these to be contained in the said range.

The light emitting layer is formed by preparing a composition for forming a light emitting layer by dissolving the above light emitting layer material in an appropriate solvent and forming a film using the composition.

As the solvent for the light emitting layer to be contained in the composition for forming a light emitting layer for forming the light emitting layer by a wet film forming method, any solvent can be used as long as the light emitting layer can be formed. Suitable examples of the solvent for the light emitting layer are the same as those described for the composition for forming a hole injection layer.

The ratio of the light emitting layer solvent to the light emitting layer forming composition for forming the light emitting layer is usually 0.01% by weight or more and usually 70% by weight or less. In addition, when using 2 or more types of solvents mixed as a solvent for light emitting layers, it is made for the sum total of these solvents to satisfy | fill this range.

After forming the light emitting layer forming composition into a wet film, the obtained coating film is dried and the solvent is removed to form a light emitting layer. The light emitting layer is similar to the coating method described in the formation of the hole injection layer, but is preferably formed by a wet film forming method from the viewpoint of reducing dark spots.

The film thickness of the light emitting layer is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the light emitting layer is too thin, defects may occur in the film, and if it is too thick, the driving voltage may increase.

* Hole blocking layer *
The hole blocking layer 6 is a layer laminated on the light emitting layer so as to be in contact with the cathode side interface of the light emitting layer. The hole blocking layer has a role of blocking holes moving from the anode from reaching the cathode and a role of efficiently transporting electrons injected from the cathode toward the light emitting layer.

The physical properties required for the material constituting the hole blocking layer include high electron mobility, low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). It is expensive. Examples of the material of the hole blocking layer satisfying such conditions include bis (2-methyl-8-quinolinolato) (4-phenolato) aluminum (PAlq) and bis (2-methyl-8-quinolinolato) (tri Mixed ligand complexes such as phenylsilanolato) aluminum (SAlq), bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, etc. Stylyl compounds such as metal complexes and distyrylbiphenyl derivatives (Japanese Patent Laid-Open No. 11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4- Triazole derivatives such as triazole (JP-A-7-41759), phenanthroyl such as bathocuproine (BCP) And the like derivatives (JP-A-10-79297). Furthermore, compounds having at least one pyridine ring substituted at the 2,4,6-positions described in International Publication No. 2005-022962 are also preferable as the material for the hole blocking layer.

In addition, only 1 type may be used for the material of a hole-blocking layer, and 2 or more types may be used together by arbitrary combinations and a ratio. Although there is no restriction | limiting in the formation method of a hole-blocking layer, It is preferable to form by the wet film-forming method from a viewpoint of dark spot reduction.

The film thickness of the hole blocking layer is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

* Electron transport layer *
The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the organic EL panel, and efficiently transports electrons injected from the cathode between the electrodes to which an electric field is applied in the direction of the light emitting layer. Formed from a compound capable of

As the electron transporting compound used for the electron transport layer, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility can be efficiently transported. Use possible compounds. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline such as Alq3 (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadi Azole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline Compound (JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous Silicon carbide, n-type sulfide Examples thereof include zinc and n-type zinc selenide.

In addition, only 1 type may be used for the material of an electron carrying layer, and 2 or more types may be used together by arbitrary combinations and a ratio.

The formation method of the electron transport layer is not limited, but it is preferably formed by a wet film formation method from the viewpoint of reducing dark spots.

The film thickness of the electron transport layer is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

* Electron injection layer *
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode into the light emitting layer. In order to perform electron injection efficiently, the material for forming the electron injection layer is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and compounds thereof (CsF _, Cs ₂ CO ₃ , Li ₂ O, LiF), and the film thickness is usually 0. .1 nm or more and 5 nm or less are preferable.

Furthermore, an organic electron transport compound typified by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium ( As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, and the like, it is possible to improve the electron injection / transport property and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

In addition, only 1 type may be used for the material of an electron injection layer, and 2 or more types may be used together by arbitrary combinations and a ratio. There is no restriction | limiting in the formation method of an electron injection layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

[Experimental Example 1]
Specifically, in the experiment, an anode (ITO) / a hole injecting layer / a hole transporting layer / a light emitting layer) / a hole blocking layer / an electron transporting layer / electron on the glass substrate by the process described above with reference to FIGS. An organic EL element having a film structure of injection layer (LiF) / cathode (Al) / was prepared and evaluated. Note that a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode were formed by an evaporation method.

From the experimental results, by arranging all the seam portions of the organic functional layer in the normal plane of the substrate, it was possible to arrange the seam portions symmetrically about the surface center of the light emitting area.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Stage 11 Stage moving mechanism 12 Inkjet head 13 Head moving mechanism

Claims (5)

1. At least one organic functional layer that is disposed on the substrate and between the first electrode layer and the second electrode layer facing each other in the normal direction of the substrate to define a light emitting area is formed by scanning a droplet discharge nozzle. An organic EL panel,
   The organic functional layer is composed of a plurality of band-like organic layers juxtaposed on the substrate and having edges joined to each other,
   The edge of the band-shaped organic layer includes one of a central straight line passing through the center of the surface of the light emitting area and two parallel lines parallel to the central straight line and separated by an equal distance from the center of the surface of the light emitting area. An organic EL panel characterized by being in a normal plane of a substrate.
2. 2. The organic EL panel according to claim 1, wherein when there are a plurality of the organic functional layers, all of the edges of the band-shaped organic layer are in a normal plane of the substrate.
3. At least one organic functional layer that is disposed on the substrate and between the first electrode layer and the second electrode layer facing each other in the normal direction of the substrate to define a light emitting area is formed by scanning a droplet discharge nozzle. An organic EL panel manufacturing method comprising:
   The first electrode layer is scanned side by side with a droplet discharge nozzle that moves on a plurality of parallel paths at equal intervals along the surface of the first electrode layer. Including a scanning step of applying a plurality of band-like organic layers bonded to each other
   In the scanning step, the droplet discharge nozzle is separated by an equal distance from the center of the surface of the light emitting area, with the edge of the strip organic layer passing through the center of the surface of the light emitting area and parallel to the center straight line. A method for manufacturing an organic EL panel, wherein the position of the substrate is controlled relative to the substrate so as to be in a normal plane of the substrate including one of two parallel lines.
4. When forming the plurality of organic functional layers by performing the scanning step a plurality of times, in each of the scanning steps, the droplet discharge nozzle is such that all the edges of the strip organic layer are within the normal plane of the substrate. The method of manufacturing an organic EL panel according to claim 3, wherein the position is controlled relative to the substrate.
5. In the scanning step, the droplet discharge nozzle individually discharges droplets of a light emitting material of at least two colors, and the droplet discharge nozzle has a band-like organic layer on the first electrode layer. 5. The method of manufacturing an organic EL panel according to claim 3, wherein the organic EL panel is controlled so as to be separated into at least two stripe shapes corresponding to light emitting materials of two or more colors.

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