JP2009128671A - Organic el display element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display element having an auxiliary electrode structure achieving resistance reduction. <P>SOLUTION: The organic EL display element includes a thin film transistor on a first substrate 101, a first electrode 110 electrically connected to the thin film transistor, a second electrode 203 facing the first electrode, and an organic light emitting layer 112 held between the first electrode and the second electrode. A second substrate 201 is arranged on the second electrode. An auxiliary electrode 202 composed of a transparent conductive film is formed on the second electrode side of the second substrate so as to cover over a light emitting surface where light from the organic light emitting layer is transmitted through the second electrode and radiated to the second substrate side. The second electrode and the auxiliary electrode are electrically connected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic EL (electroluminescence) display element, and more particularly, to a top emission type active matrix organic EL display element and a manufacturing method thereof.

  An organic EL display element is an element formed of an organic low-molecular or organic polymer having EL light-emitting ability in a light-emitting layer, and is ideal as a display element because it has a good viewing angle and excellent impact resistance due to self-emission. Has characteristics. For this reason, research and development are underway in various fields.

  The structure of the organic EL display element is basically a three-layer structure including a light emitting layer made of an organic substance and a first electrode and a second electrode sandwiching the light emitting layer. Light generated by injecting holes from one side and electrons from the other and recombining them is used.

  Incidentally, in this specification, the first electrode and the second electrode are defined so as to be counted in the stacking order from the substrate side on which the drive circuit is formed. Details of the materials used for the first electrode and the second electrode and the layer structure subdivided for improving performance will be described later.

  The organic EL display element is classified into a passive matrix EL element and an active matrix EL element according to the driving method. A passive matrix EL element is controlled for each column, whereas an active matrix EL element is characterized by including an independent switching element for each pixel.

  Active matrix EL elements are classified into a top emission system and a bottom emission system depending on the light extraction direction. Unlike the bottom emission type, the top emission type active matrix EL element takes out light from the organic light emitting layer to the second electrode side, so that the switching element located on the substrate side does not get in the way.

  Therefore, it is possible to produce an EL element having a higher aperture ratio in the top emission method than in the bottom emission method. However, the second electrode of the top emission type must be formed of a transparent material for efficient light transmission, or extremely thin so that light can be sufficiently transmitted.

Here, consider a case where the first electrode is an anode and the second electrode is a cathode. When the second electrode is formed of a transparent conductive film, the LUMO (lowest unoccupied molecular orbital) of a light emitting layer made of an organic material,
Since the work function of the second electrode cannot be matched, electrons cannot be injected efficiently.

  On the other hand, when the second electrode is formed of an extremely thin metal film, the second electrode may be short-circuited or oxidized by heat. This is because a large amount of current continuously flows through the second electrode due to the characteristics of the organic EL display element.

  Therefore, in many cases, the second electrode has a laminated structure of an extremely thin metal film and a transparent conductive film. However, in order to form an ultrathin metal film and a transparent conductive film in close contact with a light emitting layer made of an organic material, film formation with low temperature and low acceleration energy particles that do not damage the organic material is essential. Therefore, the second electrode has a specific resistance that is 100 times higher than that of a metal film such as Al.

  The organic EL display element usually has a feeding point of the second electrode at the end of the substrate. When a transparent conductive material having a large resistance is used for the second electrode, the wiring resistance value increases according to the distance from the feeding point to the pixel. As a result, the effective voltage applied to the organic EL display element constituting the pixel is lowered, and the luminance is significantly reduced.

  Various attempts to provide an auxiliary electrode have been proposed as means for avoiding the increase in resistance of the second electrode. In Patent Document 1, by providing an auxiliary common electrode, overload and short circuit of the common electrode can be prevented even if the common electrode is thin.

  In addition, there is a proposal to use a conductive light-shielding pattern as an auxiliary electrode by connecting to an upper electrode (second electrode) (Patent Documents 2 and 3).

JP 2005-56846 A JP 2005-268062 A JP 2007-141844 A

  The problem to be solved by the present invention is that the resistance reduction is insufficient in the auxiliary electrode structure applied to the conventional top emission method.

  More specifically, when an organic EL display device having a large area exceeding 40 inches is to be realized, the high resistance of the second electrode still becomes a problem. In order to reduce the resistance only in the black matrix portion serving as the light shielding area, it is necessary to change the material of the conductive material to aluminum or copper having a smaller specific resistance, or to increase the film thickness.

  In Patent Document 1 and Patent Document 3, the thickness of the auxiliary electrode formed in the light-shielding area is not exemplified in the examples. However, referring to Patent Document 2, Mo having a specific resistance of 5.6 μΩ · cm is used. The film is formed to a thickness of 300 nm. Further, if the auxiliary electrode is formed of a material having a lower resistance such as aluminum, a large organic EL display device can be expected.

  However, in the case of aluminum, there is concern about the stability of the etching process by forming an oxide coating, and switching to copper causes an increase in material and process costs. There is a limit to increasing the film thickness from the viewpoint of film stress and tact.

  Therefore, since it is not possible to cope with only a change in the method of creating the auxiliary electrode formed in the light shielding area, a new auxiliary electrode structure that realizes a lower resistance is required.

  An object of the present invention is to provide an organic EL display element having an auxiliary electrode structure that realizes a reduction in resistance and a method for manufacturing the organic EL display element.

As means for solving the above problems, the present invention provides:
A thin film transistor on a first substrate, a first electrode electrically connected to the thin film transistor, a second electrode facing the first electrode, and sandwiched between the first electrode and the second electrode An organic light emitting layer,
A second substrate is disposed on the second electrode;
A transparent conductive film is formed on the second electrode side of the second substrate so as to cover a light emitting surface through which light from the organic light emitting layer is transmitted through the second electrode and emitted to the second substrate side. An auxiliary electrode is formed,
The second electrode and the auxiliary electrode are electrically connected.

  INDUSTRIAL APPLICABILITY The present invention can provide an organic EL display element having an auxiliary electrode structure that realizes a reduction in resistance and a method for manufacturing the organic EL display element.

<Embodiment 1>
Below, Embodiment 1 of the organic EL display element which concerns on this invention is demonstrated based on drawing. FIG. 1 is a cross-sectional view of an organic EL display element. This organic EL display element has a first electrode 110 provided on the first substrate 101 and a second electrode (transparent electrode) 203 facing the first electrode 110. Furthermore, an injection layer 111 and an organic light emitting layer 112 sandwiched between the first electrode 110 and the second electrode 203 are provided.

  A second substrate 201 is disposed on the second electrode 203. A transparent conductive material is disposed on the second electrode side of the second substrate 201 so as to cover a light emitting surface through which the light from the organic light emitting layer 112 is transmitted through the second electrode 203 and emitted to the second substrate side. An auxiliary electrode 202 made of a film is formed. Incidentally, in the present embodiment, the auxiliary electrode 202 is formed so as to cover three organic EL display elements arranged side by side.

  The second electrode 203 and the auxiliary electrode 202 are electrically connected. A black matrix 205 made of a conductive member is used for connection between the auxiliary electrode 202 and the second electrode 203. The black matrix 205 also serves to separate and shield each pixel, and FIG. 1 shows a display element made of monochromatic light.

  Since the organic EL display element having the above configuration has the auxiliary electrode formed on the entire surface of the pixel, the resistance of the auxiliary electrode can be reduced. Furthermore, in the case where a transparent conductive film is formed on the second substrate as compared with the second electrode, the transparent conductive film can be formed on the second substrate 201 at a high temperature. Therefore, it is possible to form a transparent conductive film having a resistance that is one digit or more lower than that of the transparent conductive film formed as the second electrode 203 and having a high transmittance.

  The organic EL display element may have the following two laminated structures.

  The first structure is a case where the first electrode is an anode and the second electrode is a cathode. The second structure is a case where the first electrode is a cathode and the second electrode is an anode. In either case, the hole injection layer is formed between the organic light emitting layer and the anode, and the electron injection layer is formed between the organic light emitting layer and the cathode as necessary. In the above configuration, a structure having no injection layer is conceivable, and a case where the light emitting layer also serves as a transport layer is conceivable.

  FIG. 1 shows an embodiment in which the first electrode is an anode and the second electrode is a cathode. In FIG. 1, a plurality of thin film transistors (TFTs) are arranged in a matrix on a glass first substrate 101. In order to drive the TFT, the scan line and the data line are arranged at regular intervals, but are omitted from the drawing. These scan lines and data lines are arranged in a lattice pattern, and a region surrounded by the two orthogonal to each other is one pixel.

  The components of the TFT are a semiconductor layer 102, a gate insulating layer 103, a gate electrode 104, a source electrode 105 and a drain electrode 106. After the openings for the source electrode 105 and the drain electrode 106 are provided in the interlayer insulating film 108, an electrode material is formed and buried to make a contact. Further, after the via opening 107 is provided in the planarizing film 109, an electrode material to be the first electrode 110 is formed and buried.

  Here, the semiconductor layer 102 and the gate insulating layer 103 are made of polysilicon and silicon nitride (SiN), respectively. Both the source electrode 105 and the drain electrode 106 are made of an aluminum copper alloy.

  Amorphous silicon may be used as the semiconductor material. Further, although the above embodiment uses a TFT having a top gate structure, a bottom gate structure may be used. Furthermore, providing a planarization layer or the like on the substrate side for the purpose of improving switching characteristics can be easily analogized by those skilled in the art.

  Each scan line, data line, and power line are formed on the first substrate 101 (not shown). A first electrode (anode) 110 is provided for each pixel corresponding to each thin film transistor. In the case of the top emission structure, the first electrode needs a function as a reflective film for extracting light to the second electrode side. In addition, the anode material to be the first electrode preferably has a work function as large as possible in order to increase the hole injection efficiency. For example, a single metal such as gold, platinum, nickel, palladium, cobalt, selenium, vanadium is used. it can. Alternatively, metal oxides such as these alloys, tin oxide, zinc oxide, indium tin oxide (ITO), and indium zinc oxide can be used. In addition, conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyphenylene sulfide can also be used. These electrode materials may be used alone or in combination.

  In this embodiment, ITO having a thickness of 200 nm is formed on an aluminum copper alloy having a thickness of 350 nm to form the first electrode 110. As long as holes can be supplied sufficiently, the film thickness is not limited to this. The thin film transistor and the first electrode 110 are connected through a via 107.

  A partition wall 114 made of an insulator is formed around the first electrode 110 and above the thin film transistor. The purpose of the partition 114 is to separate the light emitting layer material. When a dispensing method is used to form the organic light emitting layer, it is desirable that the partition wall thickness be sufficiently thick because the dilution ratio of the organic light emitting layer material with a solvent is high.

  In this embodiment, the partition 114 is formed with a film thickness of 3000 nm. The end face shape of the partition wall 114 is preferably a trapezoidal shape with good coverage.

  Note that an auxiliary partition wall 113 made of an inorganic insulating film is provided under the partition wall 114 to enhance insulation. The auxiliary barrier 113 is made of silicon nitride (SiN) and has a thickness of 100 nm.

  After forming the first electrode 110, the auxiliary barrier 113, and the barrier 114, the organic light emitting layer 112 is formed.

  The organic light emitting layer 112 can have a structure including a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer.

  The organic compound used for the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer may be composed of a low molecular material, a polymer material, or both. There is no particular limitation.

The hole transporting material preferably has excellent mobility for facilitating the injection of holes from the anode and transporting the injected holes to the light emitting layer. Further, a hole injection layer may be sandwiched between the anode and the hole transport layer as necessary. Examples of low-molecular and high-molecular materials having hole transport performance include triarylamine derivatives, phenylenediamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, and pyrazoline derivatives;
Pyrazolone derivatives, oxazole derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly (vinylcarbazole);
Poly (silylene), poly (thiophene) and the like can be mentioned, but of course not limited thereto.

As the light emitting material, a fluorescent dye or a phosphorescent material having high light emission efficiency is used. The light emitting layer means a layer that recombines injected holes and electrons and emits light at a wavelength specific to the material. There is a case where the host material itself forming the light emitting layer emits light, and a case where a dopant material added in a small amount to the host emits light. Specific host materials include distyrylarylene derivatives (DPVBi), silole derivatives (2PSP) having a benzene ring in the skeleton, oxodiazole derivatives (EM2) having a triphenylamine structure at both ends, and perinone derivatives having a phenanthrene group (P1);
Oligothiophene derivative (BMA-3T) having a triphenylamine structure at both ends, perylene derivative (tBu-PTC), tris (8-quinolinol) aluminum, polyparaphenylene vinylene derivative, polythiophene derivative;
A polyparaphenylene derivative, a polysilane derivative, a polyacetylene derivative, etc. are mentioned, but of course, it is not limited to these.

As dopant materials, quinacridone, coumarin 6, nile red, rubrene, 4- (dicyanomethylene) -2-methyl-6- (para-dimethylaminostyryl) -4H-pyran (DCM);
A dicarbazole derivative and the like can be mentioned, but of course not limited thereto.

The electron transporting material can be arbitrarily selected from those having a function of transporting injected electrons to the light emitting layer, and is selected in consideration of the balance with the carrier mobility of the hole transporting material. Materials having electron transport performance include oxadiazole derivatives, oxazole derivatives, thiazole derivatives, thiadiazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, perylene derivatives, quinoline derivatives;
Examples include, but are not limited to, quinoxaline derivatives, fluorenone derivatives, anthrone derivatives, phenanthroline derivatives, organometallic complexes, and the like.

  Moreover, as an electron injection material, electron injection property can be provided by making the electron transport material mentioned above contain 0.1 to several tens% of an alkali metal, an alkaline earth metal, or a compound thereof. The electron injecting layer is not an indispensable layer, but taking into account the damage that occurs during film formation when a transparent cathode is subsequently formed, in order to ensure good electron injecting properties, it is not necessary to It is preferable to insert about 1 nm to 10 nm.

  Examples of the electron injection layer material include cesium carbonate, lithium fluoride, magnesium fluoride, calcium fluoride, strontium fluoride, barium fluoride, magnesium oxide, and aluminum oxide, but of course not limited thereto. .

  The organic compound thin film used for each of the above layers can generally be formed by vacuum deposition, ionization deposition, sputtering, plasma CVD, or the like. Alternatively, it may be formed by a known coating method (for example, spin coating, dispensing, dipping, casting method, LB method, ink jet method, etc.) after dissolving in an appropriate solvent. In particular, when a film is formed by a coating method, the film can be formed in combination with an appropriate binder resin.

The binder resin can be selected from a wide range of binder resins, such as polyvinyl carbazole resin, polycarbonate resin, polyester resin, polyarylate resin, polystyrene resin, ABS resin, polybutadiene resin, polyurethane resin;
Acrylic resin, methacrylic resin, butyral resin, polyvinyl acetal resin, polyamide resin, polyimide resin, polyethylene resin, polyethersulfone resin, diallyl phthalate resin, phenol resin, epoxy resin, silicone resin, polysulfone resin;
Although urea resin etc. are mentioned, it is not limited to these.

  In the present embodiment, the injection layer 111 and the organic light emitting layer 112 are formed. The injection layer 111 is a hole injection layer in this embodiment, and PEDOT / PSS was continuously applied using a dispenser device. The application conditions are as follows. A metal needle having a diameter of 80 μm processed with Teflon (registered trademark) for a width of 100 μm of the partition wall 114 is used, the distance between the needle and the surface to be coated is 30 μm in the atmosphere, and the relative speed between the needle and the substrate 101 is 450 mm. The coating was continuously performed at / sec. After coating, a 30-nm-thick hole injection layer was formed by baking at 200 ° C. for 10 minutes using a hot plate.

  As the organic light-emitting layer 112, a dispenser device is used between the partition walls 114 with a solution obtained by dissolving 1 wt% of polyparaphenylene vinylene derivative poly [2-methoxy, 5- (2′-ethylhexyoxy) -1,4-phenylene vinylene] in tetralin. And applied. The application conditions are as follows. Using a Teflon (registered trademark) -processed metal needle with a diameter of 80 μm, the distance between the needle and the surface to be coated was continuously applied in nitrogen at a distance of 30 μm and the relative speed between the needle and the substrate 101 was 300 mm / sec. . After coating, the organic light emitting layer 112 having a thickness of 100 nm was formed by baking at 150 ° C. for 30 minutes in a nitrogen atmosphere using a hot plate.

  After forming the organic light emitting layer 112, the second electrode 203 is formed by vapor deposition and sputtering. The electrode material of the second electrode 203 is preferably a material having a small work function, and is used as a single metal or a plurality of alloys such as lithium, sodium, potassium, cesium, calcium, magnesium, aluminum, indium, silver, lead, tin, and chromium. be able to. A metal oxide such as indium tin oxide (ITO) can also be used. Further, the second electrode 203 which is a cathode may have a single layer structure or a multilayer structure.

  Incidentally, if the above-described electron injection layer is provided, it is not necessary to use a material having a low work function as a condition for the cathode, and a general metal material can be used. Specifically, metals such as aluminum, indium, molybdenum and nickel, alloys using these metals, polysilicon, and amorphous silicon are desirable.

In this embodiment, cesium carbonate (Cs ₂ CO ₃ ), Al, and ITO are used. The film thickness was ₃ nm for Cs ₂ CO ₃ , 4 nm for Al, and 100 nm for ITO. A feeding point (not shown) of the display element is connected to a negative electrode of a DC power source (not shown). By forming the second electrode 203 on the feeding point, the second electrode 203 has an electrode function.

  A transparent conductive film to be the auxiliary electrode 202 is formed on the second substrate 201. As the transparent conductive film, an oxide conductive film, specifically, a compound film (ITO) of indium oxide and tin oxide, a compound film of indium oxide and zinc oxide (IZO), or the like can be used.

  The term “transparent” used in the present invention refers to having a transmittance of 70% to 100% with respect to visible light. More specifically, from the viewpoint of suppressing attenuation due to multiple reflection, The coefficient κ is 0.05 or less, preferably 0.01 or less.

  In this embodiment, ITO is formed as the auxiliary electrode 202 by sputtering. By forming the film at a substrate temperature of 250 ° C., a film having a specific resistance of 60 μΩ · cm was obtained. The film thickness was 300 nm. It is known that the film quality of the transparent conductive film varies greatly depending on the film formation conditions. In particular, the transmittance and specific resistance are films that absorb much and have high specific resistance in the case of low temperature film formation. In the present invention, since the film can be formed on the second substrate 201 at a high temperature, a film having a specific resistance smaller by one digit or more than that of the transparent conductive film formed as the second electrode 203 can be obtained.

  The black matrix 205 is formed on the auxiliary electrode 202 so that the position corresponding to the pixel of the first substrate 101 is opened, that is, disposed on the partition wall 114. The black matrix 205 uses a metal or an alloy such as Al, Cr, Ag, Cu, Mo, or Ni. A light shielding layer of a general metal film generally has a thickness of 100 nm to 150 nm. However, since the black matrix 205 functions not only as a light shield but also as a part of the auxiliary electrode, a film thickness of 100 nm to 300 nm equivalent to the second electrode 203 is desirable.

  In the present embodiment, an Al alloy is used as the material for the black matrix 205. The specific resistance of the Al alloy is 4 μΩ · cm. Here, the thickness of the black matrix 205 is 300 nm.

  The second electrode 203 and the auxiliary electrode 202 are electrically connected by facing and bonding the black matrix side of the first substrate 101 and the auxiliary electrode side of the second substrate 201 formed as described above.

  In the organic EL display element, since the material used for the organic light emitting layer 112 is weak against oxygen and water and easily deteriorates, there is a problem that the lifetime is short when used in an environment where the oxygen concentration and the water concentration are high. The upper limit of oxygen and moisture concentration at which no deterioration of the element occurs is generally 10 ppm or less. For this reason, it is necessary to surround the element periphery with an inert gas so as to be equal to or less than the above upper limit. Therefore, this problem is avoided by assembling the display element as follows.

  A UV adhesive material is applied in an annular shape to either the first substrate 101 or the second substrate 201 to form an adhesive layer (not shown). Then, the layers of the first substrate 101 and the second substrate 201 are overlapped in a reduced-pressure atmosphere while facing the film surfaces of the first substrate 101 and the second substrate 201 in an environment in nitrogen gas having an oxygen and moisture content of 10 ppm or less. In this state, the first substrate 101 and the second substrate 201 are pressed so that the second electrode 203 and the black matrix 205 are in close contact with each other, and the adhesive layer is irradiated with ultraviolet light to be cured and sealed.

  In the above, nitrogen gas, which is an inert gas, is sealed, but the present invention is not limited to this. A hygroscopic agent may be disposed in the sealed interior, or the space may be filled with another liquid or solid substance.

  The organic EL display element is driven by a driving circuit (thin film transistor) for a plurality of elements on the first substrate. FIG. 2 is a schematic diagram illustrating an example of a drive circuit for one pixel 409. A scan line 401 and a data line 402 connected to a scan line driving circuit (not shown) and a data line driving circuit (not shown) outside the display element are connected to the gate electrode and the source electrode of the first transistor 403, respectively. . When a voltage signal is input to each of the scan line 401 and the data line 402, a voltage is applied to the drain electrode of the first transistor 403. A signal is input to the gate of the second transistor 404 connected to the drain of the first transistor 403 and the capacitor 408. Then, a current flows from the source to the drain of the second transistor 404 connected to the current supply line 405 to which the power source 407 is connected, and holes are supplied to the organic light emitting layer 406 through the first electrode connected to the drain. At the same time, electrons are injected into the organic light emitting layer 406 from the second electrode connected to the power supply line at the edge of the substrate, and holes and electrons are recombined in the light emitting layer in the organic light emitting layer 406, whereby the device emits light. .

  A region where a plurality of such organic EL display elements are arranged in the same plane as pixels is a display region of the display device. FIG. 3 schematically shows a two-dimensional arrangement, that is, a matrix arrangement. The pixel shown in FIG. 3 is connected to the gate driver 503 and the source driver 504 through a wiring, and enters a light emitting state or a non-light emitting state when a driving pulse is supplied.

  FIG. 4 shows a configuration in which the display device shown in FIG. 3 is made into a panel module. The panel module 508 means a configuration in which components necessary for connection to an external device such as the interface driver 505 and the connection terminal 506 are integrated in the housing 507 in addition to the configuration shown in FIG.

  The display device may take any form as long as the display device is a television (see FIG. 5B), a display device for a PC, or a device having a portion for displaying an image. For example, a portable display device may be used. Alternatively, the display device according to the present embodiment may be used for a display unit of an electronic imaging device such as a digital camera or a mobile phone (see FIG. 5A). However, the effect of the present invention can be most enjoyed in the case of a large screen having a diagonal of 40 inches or more, and the reason will be described below.

Here, a calculation example of the voltage drop of the second electrode will be described with reference to Japanese Patent Laid-Open No. 2005-56846. As a precondition, an organic light emitting material having a high light emission efficiency of 10 cd / A per unit current was used, and the light emission luminance was set to 300 cd / m ² . Further, the allowable voltage range for performing constant current driving is set to 10V. For the display device, the aspect ratio of the screen was 9:16, and the number of pixels in the vertical and horizontal directions was 1200 dots and 2000 dots, respectively. In addition, as shown in FIG. 6, two end portions along the long side of the display area 502 are set as feeding points 501.

First, the case of only the second electrode is calculated as the simplest system. The voltage drop ΔV at the center of the display area in this case is shown in Equation (1).
ΔV = (total to center × i × r) = 1/2 × M (N + 1) × i × r (1)
N: total number of pixels in the vertical direction M: total number of pixels in the horizontal direction i: constant current value flowing through one pixel r: resistance value of the second electrode per pixel

Here, the specific resistance of the second electrode is ρ ₁ , the film thickness is t ₁ , the pixel width is horizontal w, and vertical L.

The current value per pixel is
i = 300 [cd / m ² ] / 10 [cd / A] × w × L = 30 wL [A] (2)
It becomes. The resistance value per pixel is
r = ρ ₁ × L / (w × t ₁ ) [Ω] (3)
It can be expressed. If the widths of the vertical and horizontal display areas are W ₀ and L ₀ , respectively,
w = W _0/2000 [m / dot] (4)
L = L _0/1200 [m / dot] (5)
It is.

Next, a case where a conductive black matrix is provided will be described. The film thickness t ₂ of the conductive black matrix was calculated at the same film thickness of 300 nm as that of the second electrode. In this calculation, the specific resistance of the conductive black matrix is ρ ₂ .

  Assuming an aperture ratio of 80%, the width in the vertical and horizontal directions of the conductive black matrix is 10.56%, which is the same ratio to the pixel dimensions.

The current that flows per pixel is the same as the above-described equation (2). Resistance r becomes the combined resistance of the resistance r ₂ of the resistors r ₁ and the conductive black matrix side of the second electrode side.

Since the width in the horizontal direction of the conductive black matrix can be expressed as 0.1056w, the resistance value r _{2 in} the vertical direction of the conductive black matrix is as follows.
r ₂ = ρ ₂ × L / (0.1056 w × t ₂ ) [Ω] (6)
In addition, the resistance value in pixel units on the second electrode side is
r ₁ = ρ ₁ × L / (w × t) [Ω] (7)
Therefore, the combined resistance value is
r = r ₁ × r ₂ / (r ₁ + r ₂ ) [Ω] (8)
It becomes.

  Further, in the same manner, the effect of the auxiliary electrode by the transparent conductive film provided on the second substrate is calculated.

  In this case, since the area that can be used as the auxiliary electrode is the entire surface of the pixel, there is no increase in resistance due to the wiring width as in the case of the conductive black matrix. Furthermore, compared to the second electrode, when a transparent conductive film is formed on the second substrate, it is possible to set the film forming conditions to lower resistance, so the resistance is one digit or more lower and the transmittance is higher. A transparent conductive film can be formed.

Therefore, when the resistance of the auxiliary electrode by the transparent conductive film provided on the second substrate is r ₃ and the specific resistance of the transparent conductive film is ρ ₃ , the following is obtained.
r ₃ = ρ ₃ × L / (w × t ₃ ) [Ω] (9)
Therefore, the combined resistance value is
r = r ₁ × r ₂ × r ₃ / (r ₁ × r ₂ + r ₂ × r ₃ + r ₃ × r ₁ ) [Ω] (10)
It becomes.

FIG. 7 shows the result of calculating the voltage drop ΔV based on the equations (1) to (2) and (4) to (10). ΔV ₁ , ΔV ₂ , ΔV ₃ are respectively the case of only the second electrode, the case of the second electrode and the conductive black matrix, the case of using the second electrode, the conductive black matrix, and the auxiliary electrode provided on the second substrate. (Invention).

The parameter values used are as follows.
ρ ₁ ... 600μΩ · cm
t ₁ ... 300nm
ρ ₂・ ・ ・ 4μΩ ・ cm
t ₂ ··· 300nm
ρ ₃ ... 60μΩ · cm
t ₃ ··· 300nm

In FIG. 7, in the case of ΔV ₂ (second electrode and conductive black matrix), the diagonal dimension is smaller than 50 inches, and the voltage drop has already exceeded the voltage allowable value of 10 V for constant current driving. Therefore, it becomes difficult to drive at a constant current, and there is a limitation on the enlargement of the display device. Although it is conceivable to suppress the voltage drop by increasing the film thickness, not only will the material cost and process time increase, but the substrate itself will be warped due to the influence of the metal film, resulting in trouble during assembly. .

On the other hand, in the case of ΔV ₃ (the second electrode, the conductive black matrix, and the auxiliary electrode provided on the second substrate) as proposed, the allowable voltage value of 10 V is not exceeded even at 50 inches. Therefore, a sufficiently low resistance is obtained for a display device for home use.

  Although it is considered that the effect of the present invention has been proved by the above calculation example, the calculation result varies depending on the precondition. Therefore, it is not easy to clarify the effective screen size of the present invention. However, considering the design margin based on the above calculation, the effective screen size of the present invention is 40 inches or more.

  In FIG. 1, since all the three illustrated pixels use the same organic light emitting layer 112, the obtained light emission is monochromatic, and light emission 301, 302, 303 is obtained by controlling the thin film transistor for each pixel. It is done. With the above configuration, it is possible to realize a large-area organic EL display device that can be produced at low cost and does not have a decrease in light emission luminance due to a voltage drop caused by the second electrode 203.

<Embodiment 2>
FIG. 8 shows a cross-sectional view of an organic EL display element having a different black matrix form.

  As shown in FIG. 8, a black matrix 211 made of an insulating member and a low-resistance conductive layer 204 are laminated, and a conductive via 208 is formed in the black matrix 211 to connect the second electrode 203 and the auxiliary electrode 202. It has a connected structure.

  By using a material containing a black pigment for the black matrix 211, it is possible to improve image contrast as compared with a conductive black matrix made of only metal. In the present embodiment, the black matrix 211 is formed by using a photolithography process using a material in which a black pigment such as carbon is dispersed in photosensitive polyimide. The thickness of the black matrix 211 is 3000 nm.

  As a method for forming the conductive via 208, embedding of a conductive paste by screen printing was used. The conductive paste was a cured product of silver paste, which was cured by oven drying at a temperature of 150 ° C. for 1 hour.

  The conductive layer 204 was formed by sputtering aluminum. The film thickness is 300 nm.

  Other structures are the same as in the first embodiment, and an organic EL display element is obtained.

<Embodiment 3>
FIG. 9 shows an example in which a protective film 115 made of an insulator is formed after the second electrode 203 is formed, and the second electrode 203 and the auxiliary electrode 202 are connected by penetrating the protective film 115 using conductive beads 209. It is a cross-sectional structure.

  The first substrate 101 and the second substrate 201 were formed by the same method as in the first embodiment. On the second substrate 201, silica beads or metal balls plated with gold as conductive beads 209 were dispersed in a conductive polymer and applied by spin coating, and a photolithography process was performed. As a result, the conductive beads 209 were selectively fixed on the black matrix 205. The diameter of the beads is suitably about 5 to 30 μm.

  When the first substrate 101 and the second substrate 201 were overlaid, the conductive beads 209 were pressed strongly to make holes in the protective film 115 and penetrated.

When the protective film 115 is a resin system, a process of forming a polymer at low temperature from a dimer by chemical vapor deposition such as parylene, or a technique of vaporizing a monomer material and polymerizing it by ultraviolet polymerization is practical. For example, as the protective film 115, a metal nitride film such as silicon nitride or silicon nitride oxide, a metal oxide film such as tantalum oxide, a diamond thin film;
Moreover, polymer films, such as a fluororesin, polyparaxylene, polyethylene, a silicone resin, a polystyrene resin, photocurable resin, etc. are mentioned, A several combination may be sufficient.

  Further, in order to improve the effect of suppressing oxygen permeability and moisture permeability, a film of silicon oxide, silicon nitride, or the like may be further laminated. The total thickness is suitably 0.5 μm to 2 μm. In this embodiment, polyparaxylene is used with a thickness of 1 μm.

  Other structures are the same as in the first embodiment, and an organic EL display element is obtained.

<Embodiment 4>
In FIG. 10, after forming the second electrode 203, a protective film 115 made of an insulator is formed, and the conductive film 210 is used to penetrate the protective film 115, thereby connecting the second electrode 203 and the auxiliary electrode 202. It is a cross-sectional structure of an example.

  The first substrate 101 and the second substrate 201 were formed by the same method as in the first embodiment. After the black matrix 205 was formed on the second substrate 201, cylindrical or wall-like conductive bumps 210 were formed by using a dispensing method. The material is a cured product of silver paste. The height of the conductive bump 210 is 5 μm to 30 μm. The silver paste was cured by oven drying at a temperature of 150 ° C. for 1 hour. When the first substrate 101 and the second substrate 201 were superposed, the conductive bumps 210 were strongly pressed to make holes in the protective film 115 and penetrated.

  As the protective film 115, the same polyparaxylene as in Embodiment 3 was formed to a thickness of 1 μm. Compared with the distance between the feeding point and the pixel, the height of the conductive bump 210 is negligible. Therefore, a material having a specific resistance comparable to that of the second electrode 203 may be used for the conductive bump 210.

  Other structures are the same as in the first embodiment, and an organic EL display element is obtained.

<Embodiment 5>
FIG. 11 shows a cross-sectional view of an organic EL display element provided with a color filter. Color filters 214, 215, and 216 were formed in a pixel region surrounded by the black matrix 205 using a photolithography process. FIG. 11 shows three pixels (display elements), which all emit the same color because they are made of the same material. Since the three pixels are provided with color filters 214, 215, and 216 having different spectral characteristics, corresponding light emission 304, 305, and 306 are obtained.

  When the display element emits white light, the color filter provided in the opening of the black matrix 205 forms three colors of red, green, and blue. In the case where the display element emits blue light, a color conversion filter that converts the light emission color into red, green, and blue is formed. The color filter and the color conversion filter may be provided with a region where not only red, green and blue light but also white can be obtained. Alternatively, a structure in which target light emission is obtained by stacking a plurality of filters may be employed.

  Other structures are the same as in the first embodiment, and an organic EL display element is obtained.

  In the case of full color, each pixel display element is controlled by a thin film transistor. In addition, as a selection in the case of full color, there is also a method of controlling display by using four colors, which are white pixels in addition to the above three color pixels, as one pixel.

  In the above description, the organic light emitting layer emits monochromatic light. However, if the problem of pattern separation, such as using a coating process such as inkjet or dispense, or vapor deposition using a high-precision metal mask is solved, organic light emitting in red, green, and blue for each pixel You may make it have a light emitting layer.

<Embodiment 6>
FIG. 12 is a cross-sectional view of an organic EL display element in which a filler 207 is provided between the second electrode and the auxiliary electrode.

  The filler 207 is desirably optically transparent, and chemically is desirably a stable substance that does not cause erosion to the second electrode or the color filter side. In this invention, it is set as the structure which fills an uneven | corrugated level | step difference using acrylic resin. Other structures are the same as in the first embodiment, and an organic EL display element is obtained.

  In this case, a state in which the filler 207 is confined between the auxiliary electrode 202 and the second electrode 203 as shown in FIG. There may be a color filter between the auxiliary electrode 202 and the filler 207 (not shown).

  The organic EL display element of the present invention can be used for a display device used in a television, a mobile phone, a computer, a game machine, and other various devices.

It is sectional drawing of the organic electroluminescent display element which shows Embodiment 1 of this invention. It is a schematic diagram which shows the drive circuit of the organic EL display element of this invention. It is a schematic diagram which shows the state which has arrange | positioned the circuit of FIG. 2 in the shape of a matrix as 1 pixel, and comprised the display apparatus. It is a schematic diagram which shows the structure which made the display apparatus of FIG. 3 the panel module. It is a schematic diagram which shows the example of an application product of the panel module shown in FIG. It is a schematic diagram which shows the positional relationship of the display apparatus and electric power feeding part in this invention. An example of the result of having calculated the voltage drop of the center part of the display area in this invention is shown. It is sectional drawing of the organic electroluminescent display element which shows Embodiment 2 of this invention. It is sectional drawing of the organic electroluminescent display element which shows Embodiment 3 of this invention. It is sectional drawing of the organic electroluminescence display element which shows Embodiment 4 of this invention. It is sectional drawing of the organic electroluminescent display element which shows Embodiment 5 of this invention. It is sectional drawing of the organic electroluminescent display element which shows Embodiment 6 of this invention.

Explanation of symbols

101 First substrate 102 Semiconductor layer 103 Gate insulating layer 104 Gate electrode 105 Source electrode 106 Drain electrode 107 Via opening 108 Interlayer insulating film 109 Planarization film 110 First electrode 111 Injection layer 112 Organic light emitting layer 113 Auxiliary partition 114 114 Partition 115 Protection Film 201 Second substrate 202 Auxiliary electrode 203 Second electrode 204 Conductive layer 205 Conductive black matrix 207 Filler 208 Conductive via 209 Conductive bead 210 Conductive bump 211 Insulative black matrix 214, 215, 216 Color filter or color conversion filter 301 Extraction of light from one pixel 302 Extraction of light from one pixel 303 Extraction of light from one pixel 304 Extraction of light from one pixel 305 Extraction of light from one pixel 306 Extraction of light from one pixel 401 Line 402 data line 403 first transistor 404 second transistor 405 current supply line 406 organic light emitting layer 407 power source 408 capacitor 409 drive circuit range 501 for one pixel feed point 502 display area 503 gate driver 504 source driver 505 interface driver 506 connection terminal 507 Case 508 Panel module

Claims (21)

A thin film transistor on a first substrate, a first electrode electrically connected to the thin film transistor, a second electrode facing the first electrode, and sandwiched between the first electrode and the second electrode An organic light emitting layer,
A second substrate is disposed on the second electrode;
A transparent conductive film is formed on the second electrode side of the second substrate so as to cover a light emitting surface through which light from the organic light emitting layer is transmitted through the second electrode and emitted to the second substrate side. An auxiliary electrode is formed,
The organic EL display element, wherein the second electrode and the auxiliary electrode are electrically connected.   2. The organic EL display element according to claim 1, wherein a black matrix made of a conductive member is used as means for electrically connecting the second electrode and the auxiliary electrode.   2. The organic EL display element according to claim 1, wherein a conductive via formed in a black matrix made of an insulating member is used as means for electrically connecting the second electrode and the auxiliary electrode.   2. The second electrode according to claim 1, further comprising a protective film on the second substrate side of the second electrode, wherein the second electrode and the auxiliary electrode are connected by a conductive bead penetrating the protective film. Organic EL display element.   2. The second electrode according to claim 1, further comprising a protective film on the second substrate side of the second electrode, wherein the second electrode and the auxiliary electrode are connected by a conductive bump penetrating the protective film. Organic EL display element.   The organic EL display element according to claim 1, wherein a color filter or a color conversion filter is inserted between the second electrode and the auxiliary electrode.   The organic EL display element according to claim 1, wherein a filler is inserted between the second electrode and the auxiliary electrode.   An organic EL display device comprising a plurality of the organic EL display elements according to claim 1 and a drive circuit for the organic EL display elements.   9. The organic EL display device according to claim 8, wherein the screen size is a diagonal of 40 inches or more.   A panel module comprising the interface between the organic EL display device according to claim 8 and an external device. A thin film transistor on a first substrate, a first electrode electrically connected to the thin film transistor, a second electrode facing the first electrode, and sandwiched between the first electrode and the second electrode An organic light emitting layer,
A second substrate is disposed on the second electrode;
A transparent conductive film is formed on the second electrode side of the second substrate so as to cover a light emitting surface through which light from the organic light emitting layer is transmitted through the second electrode and emitted to the second substrate side. An auxiliary electrode is formed,
An organic EL display element, wherein the second electrode and the auxiliary electrode are electrically connected by overlapping and bonding the second electrode on the first substrate and the auxiliary electrode on the second substrate. Manufacturing method.   The method for manufacturing an organic EL display element according to claim 11, wherein a black matrix made of a conductive member is used as means for electrically connecting the second electrode and the auxiliary electrode.   12. The method of manufacturing an organic EL display element according to claim 11, wherein a conductive via formed in a black matrix made of an insulating member is used as means for electrically connecting the second electrode and the auxiliary electrode. Method.   14. The method of manufacturing an organic EL display element according to claim 13, wherein a cured product of silver paste by screen printing is used as the conductive via.   The protective film on the second substrate side of the second electrode, and the second electrode and the auxiliary electrode are connected by a conductive bead penetrating the protective film. Manufacturing method of organic EL display element.   16. The method for manufacturing an organic EL display element according to claim 15, wherein silica beads plated with gold are used as the conductive beads.   The protective film on the second substrate side of the second electrode, and the second electrode and the auxiliary electrode are connected by a conductive bump penetrating the protective film. Manufacturing method of organic EL display element.   18. The method of manufacturing an organic EL display element according to claim 17, wherein a cured product of a silver paste by a dispensing method is used as the conductive bump.   The method for manufacturing an organic EL display element according to claim 11, wherein a color filter or a color conversion filter is inserted between the second electrode and the auxiliary electrode. .   The method for manufacturing an organic EL display element according to claim 11, wherein a filler is inserted between the second electrode and the auxiliary electrode.   21. The method of manufacturing an organic EL display element according to claim 20, wherein an acrylic resin is used as the filler.

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