JP2011216601A - Organic el element, organic el display device, and methods of manufacturing organic el element and organic el display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL display device with good display quality by improving the surface flatness of the film thickness of a luminescent medium layer formed of wet coating, while preventing leak current from a hole injection layer.SOLUTION: A film thickness d1 is made to satisfy a following formula, in relation to film thicknesses d2, d3 and d4: (1.5×d2)≤d1≤d3+(d4/2), where d1 is the film thickness of an upper electrode insulating layer section 103a of a first insulating layer 103 composed of an inorganic insulating layer that forms an opening, d2 is the film thickness of a hole injection layer 105 formed with an inorganic compound, d3 is the total film thickness of a function layer (hole transport layer 106) formed between the hole injection layer 105 and an organic emitting layer 107 by a wet coating method, and d4 is the film thickness of the organic emitting layer 107. Then, swelling of the opening film thickness of a wet coating layer caused by a level difference formed in the opening end of the first insulating layer 103 is suppressed, and the foregoing has an effect to prevent leak current as well.

Description

  The present invention relates to an organic EL (electroluminescence) element, an organic EL display device, a method for manufacturing an organic EL element, and a method for manufacturing an organic EL display device.

  An organic EL element has a structure in which an organic light emitting layer exhibiting at least an EL phenomenon is sandwiched between an electrode as an anode and an electrode as a cathode. When a voltage is applied between the electrodes, organic light emission occurs. Holes and electrons are injected into the layer, and the holes and electrons are recombined in the organic light emitting layer, whereby the organic light emitting layer emits light. Further, in the organic EL device, for the purpose of increasing the light emission efficiency, a hole injection layer, a hole transport layer, or an electron transport layer between the organic light emitting layer and the cathode is provided between the anode and the organic light emitting layer. A functional layer such as an electron injection layer is appropriately selected and provided. The organic light emitting layer and these functional layers such as a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer are collectively referred to as an organic light emitting medium layer.

  The organic light emitting material for forming the organic light emitting layer includes a low molecular material and a high molecular material. As a frequently used method, there is a method of forming a thin film of the low molecular material by a vacuum deposition method or the like. At this time, patterning is performed using a fine pattern mask. However, this method has a problem that patterning accuracy is less likely to increase as the substrate becomes larger. In addition, since the film is formed in a vacuum, there is a problem that the throughput is poor.

  Therefore, a method of forming a thin film by a wet coating method by dissolving a polymer material or a low molecular material in a solvent to form a coating solution has been tried. Examples of the wet coating method for forming a thin film include a spin coating method, a bar coating method, a slit coating method, and a dip coating method. However, in order to perform patterning with high definition or separate application to RGB three colors, these wet coating methods are difficult, and it is considered that thin film formation by a printing method that is good at coating and patterning is most effective.

  However, when these organic organic light-emitting materials are dissolved or dispersed in a solvent to obtain an organic light-emitting ink, the concentration needs to be about 1% because of the solubility of the organic light-emitting material. As a method for printing this organic light emitting ink, a relief printing method using an elastic rubber plate or resin plate (for example, see Patent Document 1), an ink jet method (for example, see Patent Document 2), and the like have been proposed.

  When an organic light emitting layer is formed on a substrate to be printed by these relief printing method or ink jet method, the organic light emitting ink having a concentration of about 1% is transferred to the substrate to be printed as it is. Therefore, when the organic light emitting ink is separately applied to RGB three colors, the organic light emitting ink spreads to adjacent pixels, resulting in color mixing. Therefore, a method is used in which partition walls are provided in order to suppress the spread of ink, and organic light emitting ink is printed in the pixel electrodes partitioned by the partition walls.

The ink jet method is a method in which an organic light emitting ink is dropped several times from an ink jet nozzle onto a printing site to form an organic light emitting layer. There is a distance between the nozzle and the substrate to be printed, and the ink is partitioned by a partition only by its own weight. It is formed so as to spread over the printed part.
Further, in the relief printing method, the convex portion of the relief plate is brought into contact with the portion to be printed, so that the ink spreads in the horizontal direction in the pixels surrounded by the partition by pressing the plate and filling the space formed by the partition with the relief plate. Formed as follows.

On the other hand, functional layers such as a hole injection layer and a hole transport layer are not patterned, but are formed on the entire surface of an organic EL display panel in relation to image formation, so-called solid formation, such as vacuum deposition or sputtering. Alternatively, a coating-type hole transport material has been formed using a coating method such as a spin coating method or a die coating method. This is because the hole transport layer is generally a thin film having a thickness of 100 nm or less, and the current flowing in the thickness direction is more likely to flow than the current flowing in the lateral direction of the layer. This is because it is said that it is difficult to leak outside.
However, depending on the material properties used, current leakage may occur along the partition wall, and this is the same even when a functional layer such as a hole transport layer is patterned and applied separately by a printing method.

In addition, in the method of forming a coating film by letterpress printing method or ink jet method, the coating film dries in the pixels surrounded by the partition wall, so that a phenomenon like coffee stain occurs in the periphery of the pixel, and as a result. There is a problem that the coating film thickness after drying is thin in the central part in the pixel opening, and the coating film thickness is thick in the outer peripheral part in contact with the partition wall, and the flatness deteriorates when the film thickness is increased. . For this reason, the portion where the film thickness is relatively thin in the central portion mainly emits light, resulting in a cat-like light emission shape, resulting in a decrease in pixel light emission efficiency. there were.
In addition, in an element with a small pixel light emitting area, it is necessary to compensate for the insufficient luminance due to the small light emitting area with the light emission intensity, so that a larger burden is applied to the light emitting part, resulting in a decrease in lifespan. There was also a problem that led to.

JP 2001-155858 A JP 2002-305077 A

  By the way, in the case of an inorganic compound in which the hole injection layer is formed by dry coating, even if a material that leaks along the partition is used as the hole injection layer formed on the electrode, By forming an opening made of an insulating layer inside the opening of the partition wall, if the insulating layer has a sufficient film thickness, it becomes difficult for current to flow due to local thinning of the hole injection layer, thereby preventing leakage. Is possible.

However, when the functional layer and the organic light emitting layer are subsequently formed by a wet coating method, the outer peripheral film thickness of the opening becomes thicker and the flatness deteriorates starting from the insulating layer formed inside the partition wall. There is a problem of end.
The present invention has been made in view of the above problems, and suppresses current leakage and improves the film thickness flatness of a light-emitting medium layer formed by wet coating, whereby an organic EL element having a good display quality and an organic An object of the present invention is to provide an EL display device, a method for manufacturing an organic EL element, and a method for manufacturing an organic EL element display device.

As a result of intensive studies, the inventor of the present application has determined that the film thickness of the first insulating layer having an opening with respect to the first electrode is suitable for the film thickness of the layer structure formed between the first electrode and the second electrode. It has been found that by increasing the thickness, swelling of the outer periphery of the opening of the wet coating layer due to the step formed at the end of the opening of the first insulating layer can be suppressed, and a leakage current suppressing effect can also be obtained.
That is, in order to achieve the above object, an organic EL element according to claim 1 of the present invention includes a substrate, a first electrode formed on the substrate, and a peripheral end portion of the first electrode. A first insulating layer made of an inorganic insulating layer formed around the first electrode and forming an opening in a region facing the first electrode; and formed on the first insulating layer and the first A region including a second insulating layer that forms an opening wider than the opening of the first insulating layer in a region facing the electrode, and the first electrode surrounded by the first insulating layer and the second insulating layer A light emitting medium layer in which a hole injection layer formed on an inorganic compound by a dry coating method and one or more functional layers and an organic light emitting layer formed by a wet coating method are laminated in this order. And formed on the light emitting medium layer, In an organic EL device comprising a second electrode paired with one electrode, a film thickness d1 of an insulating layer on the electrode formed on the peripheral end of the first electrode of the first insulating layer; The film thickness d2 of the hole injection layer, the total film thickness d3 of the functional layer between the hole injection layer and the organic light emitting layer, and the film thickness d4 of the organic light emitting layer are (1.5 ) × d2 ≦ d1 ≦ d3 + (d4 / 2).

The invention according to claim 2 is characterized in that a cross-sectional shape of the first insulating layer on the opening side is an inversely tapered shape or perpendicular to the upper surface of the first electrode.
The invention according to claim 3 is characterized in that the difference between the opening side end position of the first insulating layer and the opening side end position of the second insulating layer is 1.0 μm or more. Yes.
The invention according to claim 4 is characterized in that the hole injection layer is formed of one or more kinds of inorganic compounds and contains at least molybdenum.
Further, the invention according to claim 5 is characterized in that the organic EL element according to any one of claims 1 to 4 is provided as a display element.

  Moreover, the manufacturing method of the organic EL element concerning Claim 6 of this invention is the circumference | surroundings of the said 1st electrode containing the board | substrate, the 1st electrode formed on the said board | substrate, and the surrounding edge part of the said 1st electrode. A first insulating layer formed of an inorganic insulating layer that forms an opening in a region facing the first electrode, and a region formed on the first insulating layer and facing the first electrode. A second insulating layer that forms an opening wider than the opening of the one insulating layer, and a region that includes the first electrode surrounded by the first insulating layer and the second insulating layer; A light emitting medium layer formed by laminating a hole injection layer formed of an inorganic compound by a method, one or more functional layers formed by a wet coating method, and an organic light emitting layer in this order; and on the light emitting medium layer A second electrode formed and paired with the first electrode; And a film thickness d1 of an insulating layer on the electrode formed on the peripheral edge of the first electrode of the first insulating layer, and a hole injection layer. The film thickness d2, the total film thickness d3 of the functional layer between the hole injection layer and the organic light emitting layer, and the film thickness d4 of the organic light emitting layer are (1.5) × d2 ≦ d1 ≦. The first insulating layer, the hole injection layer, the functional layer between the hole injection layer and the effective light emitting layer, and the organic light emitting layer are formed so as to satisfy the relationship of d3 + (d4 / 2). It is characterized by that.

The invention according to claim 7 is characterized in that a printing method is used as the wet coating method.
Furthermore, the invention according to claim 8 is characterized in that the printing method is a relief printing method.
A method for manufacturing an organic EL display device according to a ninth aspect of the present invention is a method for manufacturing an organic EL display device including an organic EL element as a display element. It is produced using the manufacturing method of the organic EL element of any one of claim | item 8.

  According to the present invention, the film thickness d1 of the insulating layer on the electrode of the first insulating layer that forms the opening with respect to the first electrode is equal to the film thickness d2 of the hole injection layer formed of the inorganic compound, The total film thickness d3 of the functional layer formed by the wet coating method between the hole injection layer and the organic light emitting layer and the film thickness d4 of the organic light emitting layer similarly formed by the wet coating method are (1.5. Xd2) By making the thin film satisfying the relationship of ≦ d1 ≦ d3 + (d4 / 2), the swelling of the opening inner film thickness of the wet coating layer due to the step at the opening end of the first insulating layer is suppressed, In addition, it has the effect of suppressing leakage current, and as a result, uniform light emission within the pixel can be obtained, and an organic EL element and an organic EL display device with high light emission efficiency can be obtained.

It is a schematic sectional drawing which shows the panel part of the organic electroluminescent display apparatus concerning embodiment of this invention. (A) is a schematic sectional drawing which shows the pixel part of the organic electroluminescent display apparatus concerning embodiment of this invention, (b) is an enlarged view of the 103a periphery part in Fig.2 (a). It is a schematic sectional drawing which shows the TFT substrate concerning embodiment of this invention. It is the schematic which shows an example of the relief printing apparatus used in embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment, the same reference numerals are assigned to the same components.
Here, a case where the present invention is applied to an active matrix driving type organic EL panel 10 shown in FIG. 1 applied to an organic EL display device will be described. However, the present invention is not limited to this. For example, the present invention can be applied to a passive matrix driving type organic EL panel.

Hereinafter, an active matrix driving type organic EL panel 10 to which the present invention is applied will be described with reference to FIG.
FIG. 2A is a schematic cross-sectional view showing one pixel portion constituting the active matrix driving type organic EL panel 10.
The pixel portion 100 of the active matrix driving type organic EL panel 10 shown in FIG. 2A includes a TFT substrate 101 including a thin film transistor TFT, a thin film transistor TFT and a first electrode 102 (anode) provided for each pixel, and a first electrode. A first insulating layer 103 provided so as to cover an end portion of the electrode 102 and forming an opening; a second insulating layer 104 stacked on the first insulating layer 103 as a partition for separating pixels; A hole injection layer 105 formed of an inorganic compound inside a recess including the first electrode 102 formed between the second insulating layers 104 and a hole injection at the bottom of the recess formed between the second insulating layers 104. A hole transport layer 106 formed on the layer 105, an organic light emitting layer 107 formed on the hole transport layer 106, and a second electrode 108 (cathode) formed on the organic light emitting layer 107. That.

At this time, the film thickness d1 of the on-electrode insulating layer 103a, which is the upper part of the first electrode 102 of the first insulating layer 103, the film thickness d2 of the hole injection layer 105 formed of an inorganic compound, and the hole transport layer 106 The film thickness d3 of the organic light emitting layer 107 and the film thickness d4 of the organic light emitting layer 107 are formed so as to satisfy the relationship of the following formula (1).
(1.5 × d2) ≦ d1 ≦ d3 + (d4 / 2) (1)

  That is, if the film thickness difference between the film thickness d1 of the insulating layer 103a on the electrode and the film thickness d2 of the hole injection layer 105 is smaller than half of the film thickness d2 of the hole injection layer 105, it is not divided. There is a possibility that leakage current will occur. Further, when the film thickness d1 of the on-electrode insulating layer portion 103a of the first insulating layer 103 exceeds half the value of the film thickness d4 of the organic light emitting layer 107, of the organic light emitting layer 107, the on-electrode insulating layer portion 103a. Since the region formed on the upper electrode insulating layer portion 103a is swelled by an amount corresponding to the film thickness of the upper electrode insulating layer portion 103a as compared with other regions, the organic light emitting layer 107 is formed. As a result, the flatness of the light emitting region may be lowered. Therefore, the film thickness d1 of the on-electrode insulating layer 103a is limited to the above range.

Next, a substrate (back plane) 101 used in the active matrix driving type organic EL panel 10 according to the embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 3, a thin film transistor TFT and a first electrode 102 of the organic EL panel 10 are provided on a substrate (back plane) 101 used in the active matrix driving type organic EL panel 10 according to the embodiment of the present invention. The source electrode 206 of the thin film transistor TFT and the first electrode 102 of the organic EL panel 10 are electrically connected.
A TFT substrate (back plane) 101 on which the thin film transistor TFT and the active matrix driving type organic EL panel 10 formed thereon is formed is supported by a support 202.

  Any material can be used for the support 202 as long as it is a member having mechanical strength and insulation and excellent dimensional stability. For example, plastic films and sheets such as glass, quartz, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, and polyethylene naphthalate, or oxidation to these plastic films and sheets Metal oxides such as silicon and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride and aluminum nitride, metal oxynitrides such as silicon oxynitride, acrylic resins and epoxy resins Translucent base material with a single layer or laminated polymer resin film such as silicon resin or polyester resin, metal foil such as aluminum or stainless steel, sheet or plate, and aluminum film on the plastic film or sheet. It can be used beam, copper, nickel, stainless steel and metal film non-translucent substrate as a laminate of such.

  What is necessary is just to select the translucency of the support body 202 according to which surface light extraction is performed from. The support 202 made of these materials is subjected to moisture proofing treatment or hydrophobic treatment by forming an inorganic film or applying a fluororesin in order to prevent moisture from entering the organic EL panel 10. Preferably there is. In particular, it is preferable to reduce the moisture content and gas permeability coefficient of the support 202 in order to prevent moisture from entering the organic light emitting medium layer (hole injection layer 105, hole transport layer 106, and organic light emitting layer 107). .

  As the thin film transistor TFT provided over the support 202, a thin film transistor having a known structure can be used. Specifically, as shown in FIG. 3, a thin film transistor mainly composed of a region to be a source electrode 206, a region to be a drain electrode 207, an active layer 203 in which a channel region is formed, a gate insulating film 204, and a gate electrode 205. Is mentioned. The structure of the thin film transistor TFT is not particularly limited, and examples thereof include a stagger type, an inverted stagger type, a top gate type, and a coplanar type. In FIG. 3, reference numeral 208 denotes a scanning line, and 209 denotes an interlayer insulating film.

  The active layer 203 is not particularly limited, and examples thereof include inorganic semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, cadmium selenide, thiophene oligomers, poly (p-ferylene vinylene), and the like. The organic semiconductor material can be used. These active layers 203 are formed by, for example, laminating amorphous silicon by plasma CVD and ion doping; forming amorphous silicon by LPCVD using SiH 4 gas, and crystallizing amorphous silicon by solid phase growth. After silicon is obtained, ion doping is performed by ion implantation; amorphous silicon is formed by LPCVD using Si2 H6 gas and PECVD using SiH4 gas, and is annealed by a laser such as an excimer laser, and then amorphous. A method of crystallizing silicon to obtain polysilicon and then ion doping by ion doping (low temperature process); depositing polysilicon by low pressure CVD or LPCVD, and thermally oxidizing at 1000 ° C. or higher to insulate the gate Examples include a method (high temperature process) in which a film 204 is formed, an n + polysilicon gate electrode 205 is formed thereon, and then ion doping is performed by an ion implantation method.

As the gate insulating film 204, a film normally used as a gate insulating film can be used. For example, SiO2 formed by PECVD, LPCVD, etc., SiO2 obtained by thermally oxidizing a polysilicon film, etc. Can be used.
As the gate electrode 205, a material usually used as a gate electrode can be used. For example, a metal such as aluminum or copper, a refractory metal such as titanium, tantalum, or tungsten, polysilicon, or a silicide of a refractory metal. And polycide.
As the source electrode 206 and the drain electrode 207, those normally used as the source electrode and the drain electrode can be used. For example, metals such as aluminum and copper, titanium, tantalum, tungsten, and the like can be used.

Note that the thin film transistor TFT may have a single gate structure, a double gate structure, or a multi-gate structure in which three or more gate electrodes 205 are formed. Moreover, you may have a LDD structure and an offset structure. Further, two or more thin film transistors may be arranged in one pixel.
The organic EL panel 10 according to the embodiment of the present invention needs to be connected so that the thin film transistor TFT functions as a switching element of the organic EL panel 10, and the source electrode 206 of the thin film transistor TFT and the pixel electrode of the pixel unit 100 (First electrode 102) is electrically connected.

Next, the first electrode 102 of the pixel portion 100 that electrically connects the source electrode 206 of the thin film transistor TFT will be described.
As shown in FIG. 2, the first electrode 102 is formed on the TFT substrate 101, and patterning is performed according to the pixel to be formed. The patterned first electrode 102 is partitioned by a partition wall, which will be described later, and becomes the first electrode 102 corresponding to each pixel.

  Examples of the material of the first electrode 102 include metal composite oxides such as ITO (indium tin composite oxide), indium zinc composite oxide and zinc aluminum composite oxide, metal materials such as gold and platinum, and these metal oxides. Alternatively, a single layer or a laminate of fine particle dispersion films in which fine particles of a metal material are dispersed in an epoxy resin or an acrylic resin can be used. When the first electrode 102 is used as an anode, it is preferable to select a material having a high work function such as ITO. In the case of a so-called bottom emission structure in which light is extracted from below, it is necessary to select a light-transmitting material. If necessary, in order to reduce the wiring resistance of the first electrode 102, a metal material such as copper or aluminum may be provided as an auxiliary electrode.

  The first electrode 102 can be formed by a dry film forming method such as a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method, depending on the material for forming the first electrode 102. Alternatively, a wet film forming method such as a gravure printing method or a screen printing method can be used. As a patterning method for the first electrode 102, an existing patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method is used depending on the material for forming the first electrode 102 and the film forming method. be able to. In the case where a substrate on which a thin film transistor TFT is formed is used as a substrate, it is formed so as to be conductive corresponding to the lower layer pixel.

Next, a method for forming the first insulating layer 103 and the second insulating layer 104 of the pixel portion 100 will be described.
The first insulating layer 103 of the pixel unit 100 according to the embodiment of the present invention is formed so as to cover the end of the first electrode 102 and partition the light emitting region corresponding to the pixel (first electrode 102). The second insulating layer 104 is formed so as to recede 1.0 μm or more from the end portion of the first insulating layer 103, and the first stage is composed of the first insulating layer 103 when viewed from the first electrode 102 side, and the second stage is the first A two-stage partition consisting of two insulating layers 104 is formed.

As a method for forming the first insulating layer 103 and the second insulating layer 104, an inorganic film is uniformly formed on a substrate on which the first electrode 102 is formed on the TFT substrate 101, and a resist is used. Examples thereof include a method of performing dry etching after masking, and a method of laminating a photosensitive resin on a substrate to form a predetermined pattern by photolithography.
In the case where the two-stage partition wall according to this embodiment is formed, an inorganic material is used for the first insulating layer 103 and a photosensitive resin is used for the second insulating layer 104. In forming the first insulating layer 103, it is also conceivable that only the on-electrode insulating layer portion 103a, which is a portion on the first electrode 102, of the first insulating layer 103 is separately formed by the same method.

Here, the film thickness d1 of the on-electrode insulating layer 103a of the first insulating layer 103 includes the film thickness d2 of the hole injection layer 105 formed of an inorganic compound, the film thickness d3 of the hole transport layer 106, and organic It is a thin film that satisfies the relationship of the above formula (1) with respect to the film thickness d4 of the light emitting layer 107.
Further, according to the hole injection property and electrical characteristics of the inorganic material of the hole injection layer 105, as shown in FIG. 2B, the end of the first insulating layer 103 on the first electrode 102 side, that is, on the electrode. The end portion of the insulating layer portion 103a may be formed so as to be thinner toward the end portion side, that is, the cross-sectional shape may be a reverse taper shape in which the upper side is long and the lower side is short in FIG. This reverse taper shape may be formed by anisotropic etching, for example.

FIG. 2B is an enlarged view of only the periphery of the on-electrode insulating layer 103a.
When the film thickness of the insulating layer 103a on the electrode of the first insulating film 103 is smaller than the film thickness defined by the above formula (1), a leak in the lateral direction occurs from the hole injection layer 105, and the efficiency, This will cause a decrease in the service life. In the case where an inorganic material having a high hole injection property is used as the hole injection layer 105, the cross section of the first insulating film 103 has a reverse tapered shape within the range defined by the above equation (1). By doing so, it is possible to suppress leakage.

  In the case where the film thickness of the insulating layer 103a on the electrode is larger than the film thickness defined by the above formula (1), the first electrode of the first insulating layer 103 is formed in the film forming process by the wet coating method in the subsequent process. The flatness of the organic layer in the pixel opening surrounded by the first insulating layer 103 is deteriorated due to the coating from the end portion on the side 102. When the condition of the above expression (1) is satisfied, there is no current leakage, and a structure with good flatness of the organic layer in the pixel opening can be obtained. Further, the second insulating layer 104 is formed so as to recede from the end of the first insulating layer 103 by 1.0 μm or more. Therefore, it is possible to increase the flatness.

  A preferred height of the second insulating layer 104 is about 0.5 μm to 2 μm. If the height of the second insulating layer 104 is higher than 2 μm, the formation and sealing of the second electrode 108 is hindered, and if it is lower than 0.5 μm, the peripheral edge of the pixel electrode (first electrode 102) cannot be covered. This is because when the organic light emitting layer or the like is formed, the adjacent pixels are short-circuited or mixed in color.

Next, a method for forming an organic light emitting medium layer such as the organic light emitting layer 107 of the pixel unit 100 according to the embodiment of the present invention will be described.
After forming the first insulating layer 103 and the second insulating layer 104 described above, the hole injection layer 105 is formed at least on the region corresponding to the first electrode 102 using an inorganic compound. When an inorganic material is used as the hole injecting material, the inorganic materials include Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeO _x (x ≧ 0.1) NiO, CoO, Pr ₂ O ₃ , Ag _{2. O, MoO 2, Bi 2 O} 3, ZnO, TiO 2, SnO 2, ThO 2, V 2 O 5, Nb 2 O 5, Ta 2 O 5, MoO 3, WO 3, vacuum deposition by using a MnO ₂ It is formed by the method or sputtering method. However, the material is not limited to these. As a result, the hole injection layer 105 is formed in a region corresponding to the upper surface of the first electrode 102 corresponding to the bottom surface of the recess formed between the second insulating layers 104 and the side surface of the second insulating layer 104.

  After forming the hole injection layer 105, the hole transport layer 106 is formed. The hole transport layer 106 is stacked on a hole injection layer 105 in a recess formed between the second insulating layers 104. As a material used when forming the hole transport layer 106, an aromatic amine such as polyvinyl carbazole or a derivative thereof, a polyarylene derivative having an aromatic amine in a side chain or a main chain, an arylamine derivative, or a triphenyldiamine derivative is used. Examples thereof include polymers. These materials are dissolved or dispersed in a solvent, and are formed by various coating methods using a spin coater or the like, various printing methods such as a relief printing method and an ink jet method.

After forming the hole transport layer 106, the organic light emitting layer 107 is formed. The organic light emitting layer 107 is laminated on the hole transport layer 106 in the recess formed between the second insulating layers 104.
The organic light emitting layer 107 is a layer that emits light when an electric current is passed. The organic light emitting material forming the organic light emitting layer 107 is, for example, a coumarin, perylene, pyran, anthrone, porphyrene, quinacridone, N, N Dispersing luminescent dyes such as' -dialkyl-substituted quinacridone, naphthalimide-based, N, N'-diaryl-substituted pyrrolopyrrole, iridium complex in polymers such as polystyrene, polymethyl methacrylate, polyvinyl carbazole, etc. , Polyarylene-based, polyarylene vinylene-based, and polyfluorene-based polymer materials.

These organic light emitting materials are dissolved or stably dispersed in a solvent to form an organic light emitting ink. Examples of the solvent for dissolving or dispersing the organic light emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or a mixed solvent thereof. Among them, aromatic organic solvents such as toluene, xylene, and anisole are preferable from the viewpoint of the solubility of the organic light emitting material. Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added to organic luminescent ink as needed.
Here, in the embodiment of the present invention, the hole transport layer 106 is formed as a functional layer in addition to the hole injection layer 105, but these layer configurations may be appropriately selected according to the material used. preferable. For example, an electron transport layer and / or an electron injection layer may be further provided between the organic light emitting layer 107 and the second electrode 108 serving as a cathode.

Next, a relief printing apparatus 300 will be described with reference to FIG. 4 as an example of an apparatus used when forming the hole transport layer 106 and the organic light emitting layer 107 when using an organic material.
4 shows a TFT substrate 101 on which the above-described pixel electrode (first electrode 102) and second insulating layer 104 as a partition, for example, a hole transport layer 106 made of an inorganic material, are formed as a substrate to be printed 307. This is a relief printing apparatus 300 for pattern-printing an organic light-emitting ink made of an organic light-emitting material on the TFT substrate 101.

The relief printing apparatus 300 includes an ink tank 301, an ink chamber 302, an anilox roll 303, and a printing copper 306 on which a relief printing plate 305 having an image line portion formed in a convex shape is mounted. The ink tank 301 contains an organic light emitting ink diluted with a solvent, and the organic light emitting ink is fed into the ink chamber 302 from the ink tank 301. The anilox roll 303 is rotatably supported in contact with the ink supply unit of the ink chamber 302.
A convex image line portion is formed on the plate 305 in advance according to the pattern of the first electrode 102 as a pixel electrode formed on the TFT substrate 101 in advance.

  Along with the rotation of the anilox roll 303, the organic light emitting ink is supplied to the surface of the anilox roll 303 by the ink chamber 302, and the ink layer 304 of the supplied organic light emitting ink is formed with a uniform film thickness. The ink of the ink layer 304 is transferred to a convex portion as an image line portion of a plate 305 mounted on a plate cylinder 306 that is driven to rotate in the vicinity of the anilox roll 303, and is a printed substrate placed on a flat table 308. Pattern printing is performed on a region 307 surrounded by the second insulating layer 104 as a partition wall, that is, above the first electrode 102 serving as a pixel electrode, whereby a pixel portion is formed.

Next, the second electrode 108 is formed. When the second electrode 108 is a cathode, a substance having a high electron injection efficiency into the organic light emitting layer 107 and a low work function is used. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by several nanometers at the interface in contact with the light emitting medium, and Al or Cu having high stability and conductivity is laminated. You may use it. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al ,
An alloy system of Cu with a metal element may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.

As a method for forming the second electrode 108, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on a material to be the second electrode 108.
The organic EL panel 10 can emit light by sandwiching a light emitting material between electrodes and passing an electric current, but the organic light emitting material is easily deteriorated by moisture and oxygen in the atmosphere. For this reason, normally, a sealing body (not shown) for shielding from the outside is provided. The sealing body can be manufactured, for example, by providing a resin layer on a sealing material.

The sealing material needs to be a base material having low moisture and oxygen permeability. Examples of the material include ceramics such as alumina, silicon nitride, and boron nitride, glass such as alkali-free glass and alkali glass, quartz, and moisture resistant film. Examples of moisture-resistant films include films formed by CVD of SiOx on both sides of plastic substrates, films with low permeability and water-absorbing films, or polymer films coated with a water-absorbing agent. The water vapor transmission rate is preferably 10 ⁻⁶ g / m ² / day or less.

  As an example of the material of the resin layer, a photo-curing adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin, or an ethylene ethyl acrylate (EEA) made of epoxy resin, acrylic resin, silicon resin, or the like 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. Examples of methods for forming a resin layer on a sealing material include solvent solution method, extrusion lamination method, melting / hot melt method, calendar method, nozzle coating method, screen printing method, vacuum laminating method, hot roll laminating method, etc. Can be mentioned. A material having a hygroscopic property or an oxygen absorbing property may be contained as necessary. Although the thickness of the resin layer formed on a sealing material is arbitrarily determined by the magnitude | size and shape of the organic electroluminescent panel 10 to seal, about 5 micrometers-about 500 micrometers are desirable. In addition, although it formed as a resin layer on the sealing material here, it can also form directly in the organic EL panel side.

  Finally, the organic EL panel 10 and the sealing body are bonded together in a sealing chamber. When the sealing body has a two-layer structure of a sealing material and a resin layer, and a thermoplastic resin is used for the resin layer, it is preferable to perform only pressure bonding with a heated roll. When a thermosetting adhesive resin is used, it is preferable to perform heat curing at a curing temperature after pressure bonding with a heated roll. In the case where a photocurable adhesive resin is used, curing can be performed by further irradiating light after pressure bonding with a roll.

Examples of the present invention and comparative examples are shown below.
Example 1
As the TFT substrate 101 shown in FIG. 1, an active matrix substrate provided with a thin film transistor TFT provided on a support 202 and functioning as a switching element was used. The size of the TFT substrate 101 is 200 mm × 200 mm, and a 5-inch diagonal display is installed in the center thereof, and the first electrode 102 is formed above the active matrix substrate.

  As a formation method, first, an ITO film is formed to a thickness of 40 nm by using a sputtering method, and the ITO film is patterned to have a width of 25 μm by photolithography and etching with an acid solution to form the first electrode 102. A transparent electrode (pixel electrode) was formed. The number of pixels was 320 × 240.

  Next, a two-stage partition wall was formed so as to cover the end portion of the first electrode 102 provided on the TFT substrate (active matrix substrate) 101 and partition the pixels. That is, first the first insulating layer 103 was produced. The first insulating layer 103 is formed by uniformly forming an inorganic material with a thickness of 35 nm on a TFT substrate (active matrix substrate) 101 by a vacuum deposition method, masking it with a resist, and then setting the end portion of the first electrode 102 to 0. A line pattern having a width of 40 μm was formed between the first electrodes 102 by dry etching so as to cover 5 μm. At this time, the first insulating layer 103 was formed so that the cross-sectional shape of the end portion on the first electrode 102 side forming the pixel had a reverse taper shape as shown in FIG. The film thickness of 35 nm of the first insulating layer 103 is such that the film thickness of the on-electrode insulating layer portion 103a formed in an inversely tapered shape satisfies the above-described expression (1).

  A second insulating layer 104 was formed on the first insulating layer 103. The second insulating layer 104 was first formed with a thickness of 2 μm by spin-coating a photoresist material over the entire surface. Then, a second insulating layer 104 was formed by retracting the applied photoresist material by 1.0 μm from the end of the first insulating layer 103 on the first electrode 102 side by photolithography.

  Next, molybdenum oxide (MoOx) having a thickness of 20 nm is stacked as a hole injection material on the surfaces of the first electrode 102, the first insulating layer 103, and the second insulating layer 104 by a vacuum evaporation method. A hole injection layer 105 was formed. The distance between the evaporation source and the substrate was set to 300 mm, and the angle between the vapor deposition source direction and the normal direction of the substrate surface from the center of the substrate surface was set to 0 °.

  Next, the TFT substrate 101 formed up to the above-described hole injection layer 105 using an ink in which a polyvinyl carbazole derivative, which is a hole transport material, is dissolved in toluene so as to have a concentration of 0.5% is formed on the substrate 307 to be printed. As a result, the hole transport layer 106 was printed by a relief printing method in accordance with the line pattern just above the first electrode 102 sandwiched between the first insulating layers 103. The thickness of the hole transport layer 106 after printing and drying was 20 nm.

Next, the TFT substrate 101 formed up to the above-described hole transport layer 106 is printed substrate 307 using organic light emitting ink in which polyphenylene pinylene derivative, which is an organic light emitting material, is dissolved in toluene so as to have a concentration of 1%. Is set in the relief printing apparatus 300, and is printed with the aim film thickness of 80 nm at the center of the pixel by the relief printing method in accordance with the line pattern just above the first electrode 102 sandwiched between the first insulating layers 103. went.
In Example 1, the thickness d1 of the on-electrode insulating layer portion 103a of the first insulating layer 103 is the thickness d2 of the hole injection layer 105, the thickness d3 of the hole transport layer 106, and the organic light emitting layer 107. The film was prepared so as to satisfy the above formula (1) with respect to the film thickness d4.

  Next, a Ba film was formed as a second electrode 108 by a vacuum evaporation method to a film thickness of 4 nm using a metal mask, and then an Al film was formed by a vacuum evaporation method to a film thickness of 150 nm using a metal mask. Then, a cap-type sealing glass and an adhesive were placed so as to cover the light emitting region, and the adhesive was thermally cured at about 90 ° C. for 1 hour, and hermetically sealed to produce an active matrix driving type organic EL panel 10. .

As a result of evaluating the active matrix driving type organic EL panel 10 created in this manner, as shown in Table 1, a region having a film thickness distribution within a target film thickness of + 10% in the center of the pixel is within the pixel. It was 73% of the total, and it was confirmed that almost the entire pixel was emitting light. In addition, the luminance at an applied voltage of 7 V was improved to 620 cd / m ² . A good light emission state was observed without any current leakage from the hole injection layer 105 along the partition walls.

(Example 2)
As Example 2, the organic EL panel 10 was manufactured under the same conditions as in Example 1 except that the thickness of the first insulating layer 103 was 25 nm and the thickness of the hole injection layer 105 was 15 nm. In Example 2, as shown in Table 1, a region having a film thickness distribution within a target film thickness of + 10% in the center of the pixel is 77% of the entire pixel, and almost the entire pixel. It was confirmed that was emitting light. Further, the luminance at an applied voltage of 7 V was 710 cd / m ^{2 and the} luminance value was improved. A good light emission state was observed without any current leakage from the hole injection layer 105 along the partition walls.

(Comparative Example 1)
As a comparative example of Example 1, the thickness of the first insulating layer 103 was 150 nm. At this time, the film thickness of the on-electrode insulating layer portion 103a is (1.5 × d2) ≧ d1. Others produced the organic EL panel 10 under the same conditions as in Example 1. In Comparative Example 1, as shown in Table 1, a region having a film thickness distribution within a target film thickness of + 10% in the central portion of the pixel is 38% in the entire pixel, and is not near the pixel end portion. It was confirmed that a light emitting region was present. The luminance at an applied voltage of 7 V was 420 cd / m ² . There was no current leak from the hole injection layer 105 along the partition.

(Comparative Example 2)
As a comparative example of Example 1, the thickness of the first insulating layer 103 was 20 nm. At this time, the film thickness of the on-electrode insulating layer portion 103a is d1 ≧ d3 + (d4 / 2). Others produced the organic EL panel 10 under the same conditions as in Example 1. In Comparative Example 2, as shown in Table 1, the region having a film thickness distribution within a target film thickness of + 10% in the center of the pixel was 78% in the entire pixel. However, light emission from the periphery of the barrier rib, which was thought to be caused by current leakage along the barrier rib, was observed from the hole injection layer 105, and good light emission characteristics were not obtained.

  Thus, the film thickness d1 of the on-electrode insulating layer 103a of the first insulating layer 103 is the film thickness d2 of the hole injection layer 105, the film thickness d3 of the hole transport layer 106, and the film thickness d4 of the organic light emitting layer 107. On the other hand, by fabricating the organic EL panel 10 so as to be a thin film satisfying the above formula (1), the film thickness flatness can be improved and current leakage can be suppressed, and an organic material having a good light emitting state can be obtained. An EL panel 10 could be obtained.

In the above embodiment, the case where one hole transport layer is provided as a functional layer between the hole injection layer and the organic light emitting layer has been described. However, the present invention is not limited to this. A plurality of hole transport layers may be provided as a functional layer between the hole injection layer and the organic light emitting layer. For example, a layer having a function of an electronic block or the like may be separately provided as the second hole transport layer.
In the above embodiment, the case where the present invention is applied to an organic EL panel of an organic EL display device has been described. However, the present invention is not limited thereto, and can be applied to, for example, a light emitting panel for illumination. It is.

10 Organic EL panel 101 TFT substrate (backplane)
102 1st electrode (pixel electrode)
103 first insulating layer 103a insulating layer on electrode 104 second insulating layer 105 hole injection layer 106 hole transporting layer 107 organic light emitting layer 108 second electrode 202 support 203 active layer 204 gate insulating film 205 gate electrode 206 source electrode 207 Drain electrode 208 Scan line 210 Partition 300 Letterpress printing device 301 Ink tank 302 Ink chamber 303 Anilox roll 304 Ink layer 305 Plate 306 Plate cylinder 307 Printed substrate 308 Flat stand

Claims (9)

A substrate,
A first electrode formed on the substrate;
A first insulating layer formed of an inorganic insulating layer that is formed around the first electrode including on the peripheral end of the first electrode and forms an opening in a region facing the first electrode;
A second insulating layer formed on the first insulating layer and forming an opening wider than the opening of the first insulating layer in a region facing the first electrode;
A hole injection layer formed on the region including the first electrode surrounded by the first insulating layer and the second insulating layer and formed of an inorganic compound by a dry coating method, and a wet coating method. A light-emitting medium layer in which one or more functional layers and an organic light-emitting layer are laminated in this order;
In an organic EL element comprising: a second electrode formed on the luminescent medium layer and paired with the first electrode;
The thickness d1 of the on-electrode insulating layer formed on the peripheral edge of the first electrode, the thickness d2 of the hole injection layer, the hole injection layer, and the organic of the first insulating layer The total film thickness d3 of the functional layer between the light emitting layer and the film thickness d4 of the organic light emitting layer satisfy a relationship of (1.5) × d2 ≦ d1 ≦ d3 + (d4 / 2). An organic EL element.   2. The organic EL element according to claim 1, wherein a cross-sectional shape of the first insulating layer on the opening side is a reverse taper shape or perpendicular to an upper surface of the first electrode.   The difference between the opening side end position of the first insulating layer and the opening side end position of the second insulating layer is 1.0 μm or more. Organic EL element.   The organic EL element according to any one of claims 1 to 3, wherein the hole injection layer is formed of one or more kinds of inorganic compounds and contains at least molybdenum.   An organic EL display device comprising the organic EL element according to any one of claims 1 to 4 as a display element. A substrate,
A first electrode formed on the substrate;
A first insulating layer formed of an inorganic insulating layer that is formed around the first electrode including on the peripheral end of the first electrode and forms an opening in a region facing the first electrode;
A second insulating layer formed on the first insulating layer and forming an opening wider than the opening of the first insulating layer in a region facing the first electrode;
A hole injection layer formed on the region including the first electrode surrounded by the first insulating layer and the second insulating layer and formed of an inorganic compound by a dry coating method, and a wet coating method. A light-emitting medium layer in which one or more functional layers and an organic light-emitting layer are laminated in this order;
A method of manufacturing an organic EL device comprising: a second electrode formed on the luminescent medium layer and paired with the first electrode;
The thickness d1 of the on-electrode insulating layer formed on the peripheral edge of the first electrode, the thickness d2 of the hole injection layer, the hole injection layer, and the organic of the first insulating layer The total film thickness d3 of the functional layer between the light emitting layer and the film thickness d4 of the organic light emitting layer satisfy a relationship of (1.5) × d2 ≦ d1 ≦ d3 + (d4 / 2). A method for producing an organic EL element, comprising producing the first insulating layer, the hole injection layer, the functional layer between the hole injection layer and the effective light emitting layer, and the organic light emitting layer.   The method for producing an organic EL element according to claim 6, wherein a printing method is used as the wet coating method.   The method for producing an organic EL element according to claim 7, wherein the printing method is a relief printing method. A method of manufacturing an organic EL display device including an organic EL element as a display element,
A method for manufacturing an organic EL display device, wherein the organic EL element is manufactured using the method for manufacturing an organic EL element according to any one of claims 6 to 8.

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