JP2006236819A - Film formation method, organic compound layer and display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film formation method capable of equalizing film thickness of an organic compound layer. <P>SOLUTION: A plurality of pixel electrodes 3 are patterned into a matrix-like shape, and the pixel electrodes 3 are made lyophilic by a low-pressure oxygen plasma method or an ultraviolet-ray/ozone method. A hole transportation layer 4a is formed on each pixel electrode 3. After the formation of the hole transportation layer 4a, an upper layer formed of a solution of a material identical to that of the hole transportation layer 4a is formed on the hole transportation layer 4a to form a hole transportation layer 4b. Thereafter, a luminescent layer 5 is formed on the hole transportation layer 4b, and a counter electrode 6 is formed on the luminescent layer 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film forming method for forming an organic compound layer on an electrode, an organic compound layer formed by the film forming method, and a display panel having the organic compound layer.

  The organic electroluminescence element has a laminated structure in which an organic compound layer is interposed between an anode and a cathode, and emits light in the organic compound layer when a positive bias voltage is applied between the anode and the cathode. An electroluminescence display panel that realizes image display by arranging a plurality of such organic electroluminescence elements in a matrix on a substrate as sub-pixels that emit light in any of red, green, and blue has been realized.

Moreover, when the electrode is made lyophilic by performing oxygen plasma treatment on the electrode applied before the application of the organic compound solution, and then the organic compound solution is applied to the electrode, the organic compound solution applied to the electrode is spread over the entire anode. An organic compound layer that spreads and has a uniform thickness can be formed (see, for example, Patent Document 1).
JP 2000-353594 A (paragraph [0021])

However, even if the electrode is made lyophilic by the oxygen plasma treatment, the lyophilicity of the electrode gradually decreases with time. In other words, the lyophilicity of the electrode is reduced during the formation of the organic compound layer, so the film thickness of the organic compound layer may not be uniform, and the film is formed without the organic compound layer being formed on a part of the electrode. Defects may occur. In particular, when the organic compound layer material has high cohesiveness, the film thickness in the pixel region becomes uneven, affecting the display characteristics.
Moreover, it was difficult to selectively make the partition walls liquid-repellent.

  Therefore, the present invention has been made to solve any of the above-described problems, and provides a film forming method, an organic compound layer, and a display panel that can suppress unevenness in the film thickness of the organic compound layer. For the purpose.

In order to solve the above problems, the invention according to claim 1 is a film forming method for forming an organic compound layer, wherein a first solution containing an organic compound is applied on an electrode and dried. A first film forming step of forming an organic compound layer; and applying a second solution containing the organic compound on the first organic compound layer, and forming a second material comprising the same material as the first organic compound layer And a second film forming step of forming an organic compound layer.
The invention according to claim 2 is characterized in that, in the first film forming step, the first solution is applied to the entire exposed portion of the electrode.
The invention according to claim 3 is characterized in that the electrode is lyophilic.
The invention according to claim 4 is characterized in that at least one of the first solution and the second solution is partitioned by a partition wall having liquid repellency.
The invention according to claim 5 is characterized in that the first organic compound layer is thinner than the second organic compound layer.
The invention according to claim 6 is a film forming method for forming an organic compound layer, wherein a first film forming step of forming a first organic compound layer by applying a first solution containing an organic compound on an electrode; A second solution containing the organic compound is applied onto the first organic compound layer, and the second organic compound layer is made of the same material as the first organic compound layer and is thicker than the first organic compound layer. And a second film forming step for forming a film.
The invention according to claim 7 is characterized in that in the first film forming step, the first solution is applied to the entire exposed portion of the electrode.
The invention according to claim 8 is characterized in that the electrode is lyophilic.
The invention according to claim 9 is characterized in that at least one of the first solution and the second solution is partitioned by a partition wall having liquid repellency.
The invention according to claim 10 is a film forming method for forming an organic compound layer, wherein a first application step of applying a first solution containing an organic compound and a solvent on an electrode, and an evaporation step of evaporating the solvent, And a second coating step in which a second solution containing the organic compound is further coated on the electrode after the solvent evaporates.
The invention according to claim 11 is characterized in that, in the first application step, the first solution is applied to the entire exposed portion of the electrode.
The invention according to claim 12 is characterized in that the electrode is subjected to a lyophilic treatment.
The invention according to claim 13 is characterized in that at least one of the first solution and the second solution is partitioned by a partition wall having liquid repellency.
The invention according to claim 14 is an organic compound layer, and is formed by the film forming method according to any one of claims 1 to 13.
A fifteenth aspect of the present invention is a film forming method, wherein a conductive layer is selectively coated with a liquid repellent conductive layer.
The invention according to claim 16 is characterized in that the liquid repellent conductive layer is a triazyl compound.
The invention according to claim 17 is characterized in that the partition wall is a partition wall that partitions a charge transporting solution to be a charge transport layer.
The invention according to claim 18 is characterized in that the partition is a voltage line for applying a voltage to one electrode of the organic EL element.
The invention according to claim 19 is characterized in that the one electrode is a transparent electrode.
The invention according to claim 20 is a display panel, comprising: a liquid repellent conductive layer; a partition coated with the liquid repellent conductive layer; and an organic EL element comprising a charge transport layer disposed between the partitions. It is characterized by providing.
The invention according to claim 21 is characterized in that the partition is a conductor.
The invention according to claim 22 is characterized in that the liquid repellent conductive layer is a triazyl compound.
The invention according to claim 23 is characterized in that the partition wall is a partition wall for partitioning a charge transporting solution to be a charge transport layer.
The invention according to claim 24 is characterized in that the partition is a voltage line for applying a voltage to one electrode of the organic EL element.
The invention according to claim 25 is characterized in that the one electrode is a transparent electrode.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for implementing the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

[First embodiment]
1 is a plan view of an electroluminescence display panel 1 according to the first embodiment, FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and FIG. It is arrow sectional drawing of the surface along cutting line III-III.

  As shown in FIGS. 1 to 3, in the electroluminescence display panel 1, a plurality of organic EL elements 11 are arranged on a substrate 2. Each organic EL element 11 includes a pixel electrode 3, a hole transport layer 4, a light emitting layer 5, and a counter electrode 6. A plurality of partition walls 7 formed on the protrusions along the vertical direction are arranged in parallel with each other on the substrate 2. Between adjacent partition walls 7, a plurality of pixel electrodes 3 functioning as anodes are arranged in a line along the vertical direction (column direction), and the plurality of pixel electrodes 3 formed on the substrate 2 as a whole are arranged in a matrix. Is arranged.

  The partition wall 7 is made of an inorganic material such as silicon nitride or silicon oxide, or made of a resin such as polyimide.

The pixel electrode 3 is made of a material that easily transports holes to the hole transport layer 4, for example, tin-doped indium oxide (ITO), zinc-doped indium oxide, indium oxide (In ₂ O ₃ ), tin oxide ( SnO ₂ ), zinc oxide (ZnO) or cadmium-tin oxide (CTO).

  A hole transport layer 4 is formed on the pixel electrode 3. The hole transport layer 4 is divided by the partition walls 7, and a plurality of pixel electrodes 3 arranged in a line in the vertical direction are collectively covered by the common hole transport layer 4. The hole transport layer 4 is formed by a wet coating method, and includes, for example, PEDOT (polythiophene) that is a conductive polymer and PSS (polystyrene sulfonic acid) that is a dopant.

  A light emitting layer 5 is formed on the hole transport layer 4, and a plurality of light emitting layers 5 are arranged in a line along the vertical direction between adjacent partition walls 7. One light emitting layer 5 faces one pixel electrode 3 with the hole transport layer 4 interposed therebetween, and a plurality of light emitting layers 5 are arranged in a matrix as the entire substrate 2. The light emitting layers 5 arranged in a line in the vertical direction all emit light of the same color, but the arrangement of the light emitting layers 5 in the horizontal direction follows the order of red light emission, green light emission, and blue light emission from left to right or from right to left. It is repeating. The light emitting layer 5 is formed by a wet coating method, and includes, for example, a light emitting material having a conjugated double bond such as a polyfluorene type.

  On the light emitting layer 5, the counter electrode 6 which functions as a cathode is formed. The counter electrode 6 is formed on one surface over the partition wall 7 and covers all the light emitting layers 5 together. The counter electrode 6 is formed of a material having a work function lower than that of the pixel electrode 3, and is formed of, for example, a simple substance or an alloy containing at least one of indium, magnesium, calcium, lithium, barium, and a rare earth metal. The counter electrode 6 may have a laminated structure in which layers of the above various materials are laminated, or may have a laminated structure in which a metal layer is laminated in addition to the above layers of various materials. For example, the counter electrode 6 may be composed of a low work function lithium or barium lower layer stacked on the light emitting layer 5 and an aluminum upper layer stacked on the lower layer.

  As the substrate 2, a transistor array panel in which one or a plurality of thin film transistors are patterned per pixel may be used, or a transparent substrate such as glass or resin may be used.

Next, a method for manufacturing the electroluminescence display panel 1 will be described.
First, a plurality of pixels are formed on the substrate 2 by sequentially performing a vapor deposition method (for example, PVD method or CVD method such as sputtering, ion plating, vacuum deposition, etc.), a photolithography method, and an etching method on the substrate 2. The electrode 3 is patterned. When the pixel electrode 3 is made of ITO, the average roughness Ra of the surface when deposited by EB (Electron Beam) deposition, sputtering, HDAP (Highly Dense Arc Plasma) ion plating is 10.5 nm, 4.1 nm, respectively. 0.8 nm. Next, a plurality of partition walls 7 that are elongated in the vertical direction are formed by applying and patterning a photosensitive resin such as polyimide.

  Next, the substrate 2 is subjected to ultrasonic cleaning with pure water or alcohol. Next, these pixel electrodes 3 are made lyophilic by cleaning the surface on which these pixel electrodes 3 are formed. As a method for making the pixel electrode 3 lyophilic, there are a reduced pressure oxygen plasma method and an ultraviolet / ozone method, but either one may be used, or these may be used in combination. The reduced pressure oxygen plasma method is a process of cleaning the pixel electrode 3 by irradiating the pixel electrode 3 with oxygen plasma under a reduced pressure below atmospheric pressure, thereby making the pixel electrode 3 lyophilic. The ultraviolet / ozone method is a process in which the pixel electrode 3 is washed with ultraviolet rays and ozone generated thereby by irradiating the pixel electrode 3 with ultraviolet rays, thereby making the pixel electrode 3 lyophilic.

  After making the pixel electrode 3 lyophilic, a solution (hereinafter referred to as a charge transport solution) in which the raw material (PEDOT / PSS) of the hole transport layer 4 is dissolved in a solvent (pure water or alcohol, or both pure water and alcohol). The hole transport layer 4 is formed by continuously performing a wet coating process for coating the pixel electrode 3 a plurality of times, but the hole transporting solution applied between each time is dried. Specifically, this is performed as follows.

  In the first wet coating process, at least one of a dropping method using a needle, a droplet discharging method (inkjet method), a spin coating method, and a dip coating method is used. In the dropping method using a needle, the needle is placed on the pixel electrode 3 and the charge transporting solution is applied onto the pixel electrode 3 through the needle. In the droplet discharge method, one or a plurality of droplet discharge heads (inkjet heads) are used to discharge the same charge transporting solution as droplets a plurality of times toward the surface on which the pixel electrode 3 is formed. The upper layer of the hole transport layer 4 is formed thereon. At this time, by moving the substrate 2 and / or the droplet discharge head along a predetermined surface, the droplet discharge location is gradually shifted. In the spin coating method, a hole transporting solution is dropped onto the surface on which the pixel electrode 3 is formed while the substrate 2 is rotated. In the dip coating method, the substrate 2 is immersed in a charge transporting solution. In this way, the first hole transport layer 4a that is the base of the hole transport layer 4 is formed. At this time, since the pixel electrode 3 is subjected to lyophilic treatment, the hole transporting solution selectively spreads only on the pixel electrode 3 and does not spread on the partition wall 7. Since the first hole transport layer 4a may be thin enough to cover the entire surface of the pixel electrode 3, it is sufficiently thinner than the entire thickness of the hole transport layer 4. The thickness of the first hole transport layer 4a is preferably not less than the average roughness Ra of the pixel electrode 3 and not more than twice the average roughness Ra. For this reason, the amount of the solution that becomes the first hole transport layer 4a is very small, and the pixel electrode 3 can be quickly dried before the lyophilic property is lost, and the first positive electrode is uniformly distributed over the entire surface of the pixel electrode 3. The hole transport layer 4a can be formed. Therefore, the portion where the first hole transport layer 4 is not formed on the pixel electrode 3 can be almost eliminated.

  In the second wet coating step after drying the base, as in the first wet coating step, at least one of a dropping method using a needle, a droplet discharge method (inkjet method), and a spin coating method is used. The film formation method may not be the same as the first time. In the second wet coating step, a charge transporting solution to be the second hole transport layer 4b made of the same material as the first hole transport layer 4a is attached on the first hole transport layer 4a. This charge transport solution has a high affinity with the first hole transport layer 4a, and at this time, even if the pixel electrode 3 loses its lyophilic property, the charge transport solution easily oozes into the first hole transport layer 4a. Therefore, the second hole transport layer 4b has a relatively uniform film thickness with no unevenness above the first hole transport layer 4a, and is composed of the first hole transport layer 4a and the second hole transport layer 4b. The formed hole transport layer 4 can be a relatively uniform film with respect to the pixel electrode 2. In addition, if the charge transport solution that becomes the second hole transport layer 4b is set to a sufficiently high concentration, the solvent of the charge transport solution that makes the first hole transport layer 4a the second hole transport layer 4b. The amount eluted by is very small. Therefore, the amount of the charge transport solution in the second hole transport layer 4b can be made larger than the amount of the charge transport solution in the first hole transport layer 4a, and the film thickness of the second hole transport layer 4b can be reduced. It can be made sufficiently thicker than the thickness of the first hole transport layer 4a, and even if the thickness of the hole transport layer 4 is increased as a whole, the thickness can be made uniform. It should be noted that the amount of elution of the first hole transport layer 4a decreases as the concentration of the charge transport solution that becomes the second hole transport layer 4b is closer to the saturated solution, but the charge transport is performed on the first hole transport layer 4a. Since the material of the second hole transport layer 4b may be deposited in the charge transporting solution before immersing the conductive solution, it is preferable not to be too close to the saturated concentration.

  As described above, the hole transport layer 4 is formed by two wet coating processes, but the hole transport layer 4 may be formed by three or more wet coating processes. In the first wet coating process, a spin coating method is more preferable if there is no large unevenness around the pixel electrode 3. This is because the hole-transporting solution is applied to all the pixel electrodes 3 without taking time after making the pixel electrodes 3 lyophilic, and the first hole-transporting layer 4a having a very thin and uniform film thickness is formed. This is for forming a film. The second and subsequent wet coating processes are more preferably a needle dropping method or a droplet discharging method. This is because the hole transport solution can be selectively applied only to the three pixel electrodes without waste.

  After the hole transport layer 4 is formed, these light emitting layers 5 are patterned so that one light emitting layer 5 is opposed to one pixel electrode 3 through the hole transport layer 4. As a method for patterning the light emitting layer 5, it is preferable to use a dropping method using a needle or a droplet discharging method. A solution in which the material to be the light emitting layer 5 is dissolved in a solvent or dispersed without being aggregated (hereinafter referred to as a light emitting solution) does not dissolve the dried hole transport layer 4. A solvent is preferably selected. If the hole transport layer 4 is water-soluble, an organic solvent such as tetralin, tetramethylbenzene, or mesitylene is preferable.

  Next, the counter electrode 6 is formed on the entire surface by vapor deposition.

As described above, according to the present embodiment, after the pixel electrode 3 is made lyophilic, the hole transport layer 4 is formed in a plurality of wet coating processes, so the first wet coating process performs the first process. The hole transport layer 4a can be made very thin, so that the time required for forming the first hole transport layer 4a can be shortened. Therefore, the first hole transport layer 4a can be formed on the entire surface of the pixel electrode 3 before the lyophilicity of the pixel electrode 3 is lowered, and the thickness of the underlying film can be made uniform. In the second and subsequent wet coating processes, the same hole transporting solution is applied on the base, so that the solution is easy to fit into the first hole transporting layer 4a, and the second hole transporting layer 4b has a uniform film thickness. can do. Accordingly, the film thickness of the hole transport layer 4 can be made uniform as a whole.
[Second Embodiment]
FIG. 4 is a plan view showing a part of the configuration of the active matrix drive electroluminescence display panel 101 in the second embodiment, and FIG. 5 is a sectional view of the active matrix drive electroluminescence display panel 101 in the state of FIG. It is arrow sectional drawing along line VV. 6 to 10 are cross-sectional views taken along line VV in FIG. 4 showing the respective manufacturing steps of the electroluminescent display panel 101 from FIG. 5 onward.

  In the present embodiment, a red pixel Pr that is an organic EL element that emits red light, a green pixel Pg that is an organic EL element that emits green light, and a blue pixel Pb that is an organic EL element that emits blue light are formed on the substrate 2. They are arranged in a matrix. Specifically, focusing on the vertical arrangement, a plurality of red pixels Pr are arranged in a line along the vertical direction (column direction), a plurality of green pixels Pg are arranged in a line along the vertical direction, and a plurality of blue pixels Pixels Pb are arranged in a line along the vertical direction. When attention is paid to the arrangement in the horizontal direction (row direction), the red pixel Pr, the green pixel Pg, and the blue pixel Pb are repeatedly arranged in this order.

  Between the red pixel Pr, the green pixel Pg, and the blue pixel Pb, a plurality of partition walls 37 formed in a protrusion along the vertical direction partition the red pixel Pr, the green pixel Pg, and the blue pixel Pb, respectively. 2 are arranged parallel to each other. A plurality of pixel electrodes 36 functioning as anodes are arranged in a line along the vertical direction (column direction) between the adjacent partition walls 37, and the plurality of pixel electrodes 36 formed on the substrate 2 as a whole are arranged in a matrix. Is arranged.

  Next, the pixel circuit configuration of the pixel Pr, the pixel Pg, and the pixel Pb will be described. Each pixel Pr, pixel Pg, and pixel Pb have the same configuration, and each is provided with one or more transistors Tr as switching elements that are actively driven. The transistor Tr group may be composed of only an N-channel amorphous silicon thin film transistor, or may be composed of a polysilicon thin film transistor.

  The pixel circuit of each pixel may be a current gradation control type that controls the light emission luminance gradation by passing a current of a predetermined current value through the signal line, or applies a voltage signal of a predetermined voltage value to the signal line A voltage gradation control type circuit for controlling the light emission luminance gradation may be used.

  First, the structure of each transistor Tr will be described. As shown in FIG. 5, the switch transistor Tr includes a gate 21 formed on the substrate 2, a gate insulating film 22 formed on the gate 21, and a semiconductor film facing the gate 21 with the gate insulating film 22 interposed therebetween. 23, a channel protective film 24 formed on the central portion of the semiconductor film 23, and impurity semiconductor films 25 and 25 formed so as to be separated from each other on both ends of the semiconductor film 23 and partially overlapping the channel protective film 24. And a source 26 and a drain 26 formed on the impurity semiconductor films 25 and 25, respectively. In one pixel, a pixel circuit including a transistor Tr is connected to a signal line, a scanning line, and the like (not shown). The transistor Tr is covered with a protective insulating film 32 such as silicon nitride or silicon oxide.

A planarizing film 33 is stacked on the protective insulating film 32, and unevenness due to the transistors Tr, signal lines, and the like is eliminated by the planarizing film 33, so that the surface of the planarizing film 33 is flat. The flattened film 33 is preferably a film obtained by curing a photosensitive insulating resin such as polyimide.
In one pixel, a contact hole is formed in the protective insulating film 32 and the planarization film 33 so that the source or drain 26 of a predetermined transistor Tr is exposed, and a conductive layer 34 is embedded in the contact hole. A pixel electrode 36 connected to the conductive layer 34 is formed on the planarization film 33 of each pixel. A base insulating layer 35 is formed so as to overlap the peripheral edge of the pixel electrode 36 in the vertical direction. That is, the two adjacent base insulating layers 35 are continuously provided in the vertical direction along the left and right sides so as to expose the center of the pixel electrode 36 disposed therebetween. A partition wall 37 extending in the vertical direction along the base insulating layer 35 is formed on the base insulating layer 35. The partition wall 37 is made of a conductive material containing at least one of copper, gold, and silver.

  A liquid repellent conductive layer 38 having water repellency and oil repellency is formed on the surface of the partition wall 37. In the liquid repellent conductive layer 38, the hydrogen atom (H) of the thiol group (—SH) of triazyltrithiol represented by the following chemical formula (1) is reduced and released, and the sulfur atom (S) is the surface of the partition wall 37. Are combined.

Since the liquid repellent conductive layer 38 is a film made of an extremely thin molecular layer in which triazyltrithiol molecules are regularly arranged on the surface of the common wiring 91, the liquid repellent conductive layer 38 has a very low resistance and has a conductive property. Have. In order to make the water repellency and oil repellency remarkable, triazylthiol in which one or two thiol groups of triazyltrithiol are substituted with fluorinated alkyl groups may be used instead of triazyltrithiol. Such a triazyl compound can be selectively coated and bonded to a metal such as the partition wall 37. Specifically, 6-dimethylamino-1,3,5-triazine-2,4-dithiol-sodium salt or 6-didodecylamino-1,3,5-triazine-2,4-dithiol-sodium salt is used. After adjusting to a concentration of 10 ⁻³ mol / l aqueous solution, when immersed in the upper surface of the substrate 2 under conditions of a liquid temperature of 20 to 50 ° C. and an immersion time of 10 minutes to 60 minutes, a film thickness of 0. An extremely thin film of about 2 nm to 4 nm was coated. Since the liquid repellent conductive layer 38 is such an extremely thin film, it can be electrically connected to the partition wall 37 via the liquid repellent conductive layer 38 when an electric conductor is in contact with the surface of the liquid repellent conductive layer 38. Become.
Next, as shown in FIG. 6, a conductive polymer PEDOT (polythiophene) and a dopant PSS (polystyrene sulfonic acid) 0.1 wt% to 10 wt% are used as a solvent (pure water or alcohol, or both pure water and alcohol). The pixel electrode 36 is coated with the charge transporting solution 39 dissolved in at least one of a dropping method using a needle, a droplet discharging method (inkjet method), a spin coating method, and a dip coating method. At this time, the charge transporting solution 39 may run up to the base insulating layer 35, but is repelled by the liquid repellent conductive layer 38 coated on the surface of the partition wall 37. There is no leakage.

  Thereafter, as shown in FIG. 7, the charge transporting solution 39 is dried to form a first hole transport layer 40 that becomes a part of the charge transport layer. The drying step is desirably performed in a reduced pressure atmosphere, and may be heated to such an extent that the hole transport property of the first hole transport layer 40 and the liquid repellency of the liquid repellent conductive layer 38 are not reduced.

  On the surface of the partition wall 37, the liquid repellent conductive layer 38 repels the charge transport solution 39, so that the first hole transport layer 40 does not become extremely thick in the vicinity of the partition wall 37, that is, in the peripheral portion of the pixel electrode 36. For this reason, since the charge transport solution 39 does not become extremely thin at the center of the pixel electrode 36, the first hole extends from the center to the peripheral portion of the pixel electrode 36 even if the amount of the charge transport solution 39 is small. The transport layer 40 can be formed. In addition, since the thickness is relatively uniform over the entire pixel electrode 36, the evaporation rate of the solvent is also uniform, and the drying rate of the entire first hole transport layer 40 is higher than when the peripheral edge of the pixel electrode 36 is thick. Get faster.

  As described above, due to the liquid repellent effect of the small amount of the charge transport solution 39 and the liquid repellent conductive layer 38, the charge transport property is sufficiently transferred to the entire pixel electrode 36 even if the liquid repellent property of the pixel electrode 36 is reduced. The first hole transport layer 40 can be formed on the entire pixel electrode 36 by attaching the solution 39.

  Since the first hole transport layer 40 may be thin enough to cover the entire surface of the pixel electrode 36, it is sufficiently thinner than the entire thickness of the hole transport layer 43. The thickness of the first hole transport layer 40 is preferably not less than the average roughness Ra of the pixel electrode 36 and not more than twice the average roughness Ra. For this reason, the amount of the solution that becomes the first hole transport layer 40 is very small, and the pixel electrode 36 can be quickly dried before the lyophilic property is lost, and the first positive electrode is uniformly applied to the entire surface of the pixel electrode 36. The hole transport layer 40 can be formed. Therefore, the portion where the first hole transport layer 40 is not formed on the pixel electrode 36 can be almost eliminated.

  In the second wet coating step after the first hole transport layer 40 is dried, as in the first wet coating step, at least a dropping method using a needle, a droplet discharge method (inkjet method), or a spin coating method is used. Either one is used, but the film forming method is not necessarily the same as the first film formation method. In the second wet coating step, as shown in FIG. 8, the charge transport solution that becomes the second hole transport layer 42 made of the same material as the first hole transport layer 40 on the first hole transport layer 40. 41, the charge transport solution 41 has a high affinity with the first hole transport layer 40. At this time, even if the lyophilicity of the pixel electrode 36 has already been lost, the first hole transport It tends to bleed into the layer 40. In addition, the charge transporting solution 41 may run up to the base insulating layer 35, but is repelled by the liquid repellent conductive layer 38 coated on the surface of the partition wall 37. There is no end to it.

  Therefore, as shown in FIG. 9, the second hole transport layer 42 has a relatively uniform thickness without uneven coating above the first hole transport layer 40, and the first hole transport layer 40 and the second hole transport layer 40 The hole transport layer 43 composed of the hole transport layer 42 can be a relatively uniform film with respect to the pixel electrode 2. If the charge transporting solution 41 is set to a sufficiently high concentration, the amount of the first hole transporting layer 40 eluted by the solvent of the charge transporting solution 41 is extremely small. Therefore, the amount of the charge transporting solution 41 can be made larger than the amount of the charge transporting solution 39, and the film thickness of the second hole transport layer 42 is made sufficiently thicker than the film thickness of the first hole transport layer 40. As a whole, even if the thickness of the hole transport layer 43 composed of the first hole transport layer 40 and the second hole transport layer 42 is increased, a relatively uniform film thickness can be obtained. . For this reason, the hole transport property to the entire surface of the light emitting layer 44 described later becomes uniform, and the light emitting area of the light emitting layer 44 can be improved. Note that the amount of elution of the first hole transport layer 40 decreases as the concentration of the charge transport solution 41 is closer to that of the saturated solution. Since the second hole transport layer material may be deposited in the transport solution 41, it is preferable that the concentration is not too close to the saturation concentration.

  After forming the hole transport layer 43, a light emitting solution in which the material that becomes the light emitting layer 44 is melted in a solvent or dispersed without being aggregated is attached on the hole transport layer 43 between the partition walls 37 and 37. Let As a method for forming the light emitting layer 44, a dropping method using a needle or a droplet discharging method is preferably used. The light emitting layer 44 is formed by a wet coating method, and includes, for example, a light emitting material having a conjugated double bond such as polyfluorene. Since the luminescent solution is also repelled by the liquid repellent conductive layer 38 of the partition wall 37, the luminescent layer 44 can be formed on the hole transport layer 43 with a uniform thickness. Since the luminescent solution is partitioned by the partition walls 37, the light emitting layer 44 becomes a continuous film in the vertical direction along the partition walls 37 as shown in FIG. 10. That is, the light emitting layer 44 that emits red light is formed in the plurality of red pixels Pr that are continuous in the vertical direction, and the light emitting layer 44 that emits green light is formed in the plurality of green pixels Pg that are continuous in the vertical direction. In the plurality of blue pixels Pb connected to, a light emitting layer 44 that emits blue light is formed.

  A solution in which the material to be the light-emitting layer 44 is dissolved in a solvent or dispersed in a non-aggregated state (hereinafter referred to as a light-emitting solution) does not dissolve the dried hole transport layer 43. A solvent is preferably selected. If the hole transport layer 43 is water-soluble, an organic solvent such as tetralin, tetramethylbenzene, or mesitylene is preferable.

  On the light emitting layer 44, a counter electrode 45 that functions as a cathode is formed. The counter electrode 45 is formed on the entire surface over the partition wall 37 in contact with the liquid repellent conductive layer 38 and covers all the light emitting layers 44 together. The counter electrode 45 is made of a material having a work function lower than that of the pixel electrode 36, and is made of, for example, a simple substance or an alloy containing at least one of indium, magnesium, calcium, lithium, barium, and a rare earth metal. The counter electrode 45 may have a laminated structure in which the layers of the various materials are laminated, or may have a laminated structure in which a metal layer is laminated in addition to the layers of the various materials. When the counter electrode 45 is opaque, for example, it may be composed of a low work function lower layer laminated on the light emitting layer 44 and an aluminum upper layer laminated on this lower layer. Further, when the counter electrode 45 is transparent, for example, it may be composed of a low work function lower layer laminated on the light emitting layer 44 and a transparent conductive upper layer such as ITO laminated on the lower layer. The partition wall 37 is electrically connected to the counter electrode 45 through the liquid repellent conductive layer 38, and also functions as a voltage line for supplying the common voltage Vcom to the counter electrode 45. If the partition wall 37 has a low resistance, the sheet resistance of the entire electrode to which the common voltage Vcom is applied can be reduced without forming the counter electrode 45 thick. In particular, when the counter electrode 45 is transparent and the light of the light emitting layer 44 is transmitted through the counter electrode 45 and emitted, the transmittance of the counter electrode 45 can be improved. The above-mentioned triazyl compound that becomes the liquid repellent conductive layer 38 is not coated to such an extent that the liquid repellent property is expressed with respect to a transparent electrode such as ITO or chromium or aluminum, and is selective to copper, gold, or silver. In the case of a structure in which light emitted from the light emitting layer 44 is transmitted through the counter electrode 45 and emitted, the pixel electrode 36 does not need to be a transparent electrode and is formed of a metal such as chromium or aluminum. Also good.

  In the second embodiment, the partition wall 37 is provided only in the vertical direction. However, the present invention is not limited to this, and the partition wall 37 may be formed in the vertical direction and the horizontal direction. That is, as shown in FIG. 11, the base insulating layer 35 is a base insulating layer that is continuous in a matrix shape so as to expose the center of the pixel electrode 36, and the partition 37 is formed on the base insulating layer 35. Are formed continuously in a matrix. A liquid repellent conductive layer 38 is coated on the surface of the partition wall 37. Even in this case, the charge transporting solution on the pixel electrode is applied to each pixel in a plurality of times to form the charge transport layer in a plurality of times.

  The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

  In the above embodiment, the pixel electrode 3 is made lyophilic by the reduced-pressure oxygen plasma method or the ultraviolet / ozone method. Instead, a fluororesin film having a thickness of 1 nm to 15 nm showing liquid repellency is used as the partition wall 7 and the pixel. After coating on the surface of the electrode 3, a photocatalyst is selectively disposed only above the fluorine resin film on the pixel electrode 3, and the photocatalyst is activated by irradiating the photocatalyst with excitation light. A functional group exhibiting liquid repellency such as a fluorinated alkyl group may be substituted with a hydroxyl group or the like, and the upper surface and the side surface of the partition wall 7 may remain liquid repellent, and the pixel electrode 3 may be modified to be lyophilic. .

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
A substrate 102 as shown in FIG. 12 was used. On one surface of the substrate 102, an ITO electrode 103 was formed on the entire surface, and on the electrode 103, a plurality of partition walls 107 serving as protrusions were formed in parallel.

  In the example, as in the above-described embodiment, the electrode 103 was subjected to oxygen plasma treatment, and then a hole transport layer was formed through two wet coating processes. The conditions for the oxygen plasma treatment were a pressure of 50 to 100 Pa, a cathode power of 250 W, and a treatment time of less than 10 minutes. Immediately after the oxygen plasma treatment, the first wet coating process was performed, and the spin coating method was used for the first wet coating process. As conditions for the spin coating method, the concentration of the hole transporting solution was set to 0.25 wt%, the rotation number per unit time was set to 4500 rpm, and the rotation time was set to 20 seconds. The film thickness is approximately 10 nm. The substrate was dried in 20 seconds after coating, and a second wet coating process was performed after drying. A droplet discharge method was used for the second wet coating process. As conditions for the droplet discharge method, the concentration of the hole transporting solution was set to 1.25 wt%, and an upper layer of 50 nm was formed. The state after film formation is shown in the plan view of FIG.

  In the comparative example, the electrode 103 was subjected to oxygen plasma treatment, and then the hole transport layer was formed only by one wet coating process. The state after film formation is shown in the plan view of FIG.

In the comparative example, it can be seen from FIG. 14 that there is a portion 210 where the hole transport layer 204 is not formed, and the electrode 103 is exposed in the portion 210. On the other hand, in the example, it can be seen from FIG. 13 that the hole transport layer 104 is formed so as to spread over the entire electrode 103 and the film thickness is uniform.
In each of the above embodiments, the charge transporting solution that becomes the hole transporting layer is a PEDOT / PSS solution. However, if the liquid repellency on the surface of the pixel electrode is lost, it is localized on the pixel electrode. Any other hole transporting material may be used.
In each of the above embodiments, the charge transport layer formed by applying the charge transport solution formed on the pixel electrode is the hole transport layer. However, if the liquid repellency on the surface of the pixel electrode is lost, the pixel electrode The electron transport layer is not limited to this as long as it is localized above. At this time, the pixel electrode functions as a cathode, and the counter electrode functions as an anode.
Further, in each of the above embodiments, if the liquid repellency on the surface of the pixel electrode is lost, the charge transport layer formed on the pixel electrode may be used as the light emitting layer as long as it is localized on the pixel electrode.

It is a top view of the electroluminescent display panel 1 in 1st embodiment. It is arrow sectional drawing of the surface along the cutting line II-II of FIG. It is arrow sectional drawing of the surface along the cutting line III-III of FIG. It is a top view which shows a partial structure of the active matrix drive electroluminescent display panel 101 in 2nd embodiment. FIG. 5 is a cross-sectional view of a part of the active matrix drive electroluminescent display panel 101 in the state of FIG. 4 taken along a cutting line VV. FIG. 5 is a cross-sectional view of the surface along the cutting line VV in FIG. 4 showing each manufacturing process of the electroluminescence display panel 101. FIG. 5 is a cross-sectional view of the surface along the cutting line VV in FIG. 4 showing each manufacturing process of the electroluminescence display panel 101. FIG. 5 is a cross-sectional view of the surface along the cutting line VV in FIG. 4 showing each manufacturing process of the electroluminescence display panel 101. FIG. 5 is a cross-sectional view of the surface along the cutting line VV in FIG. 4 showing each manufacturing process of the electroluminescence display panel 101. FIG. 5 is a cross-sectional view of the surface along the cutting line VV in FIG. 4 showing each manufacturing process of the electroluminescence display panel 101. FIG. 10 is a plan view showing a partial configuration of an active matrix drive electroluminescence display panel 101 showing a modification of the second embodiment. It is sectional drawing of the board | substrate 102 and the electrode 103 which were used for the Example and the comparative example. It is the top view which showed the state after forming the positive hole transport layer 104 in the Example. It is the top view which showed the state after forming the positive hole transport layer 204 in a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electroluminescent display panel 2 Substrate 3 Pixel electrode 4 Hole transport layer 4a First hole transport layer 4b Second hole transport layer 7 Partition 11 Organic EL element 37 Partition 36 Pixel electrode 38 Liquid repellent conductive layer 40 First positive Hole transport layer 42 Second hole transport layer 43 Hole transport layer 101 Electroluminescence display panel

Claims (25)

In a film forming method for forming an organic compound layer,
A first film forming step of forming a first organic compound layer formed by applying a first solution containing an organic compound on an electrode and drying the solution;
Applying a second solution containing the organic compound on the first organic compound layer and forming a second organic compound layer made of the same material as the first organic compound layer;
A film forming method comprising:   2. The film forming method according to claim 1, wherein in the first film forming step, the first solution is applied to an entire exposed portion of the electrode.   The film forming method according to claim 1, wherein the electrode is lyophilic.   4. The film forming method according to claim 1, wherein at least one of the first solution and the second solution is partitioned by a partition wall having liquid repellency. 5.   The film forming method according to claim 1, wherein the first organic compound layer is thinner than the second organic compound layer. In a film forming method for forming an organic compound layer,
A first film forming step of forming a first organic compound layer by applying a first solution containing an organic compound on an electrode;
On the first organic compound layer, a second solution containing the organic compound is applied to form a second organic compound layer made of the same material as the first organic compound layer and thicker than the first organic compound layer. A second film forming step of forming a film;
A film forming method comprising:   The film forming method according to claim 6, wherein in the first film forming step, the first solution is applied to an entire exposed portion of the electrode.   The film forming method according to claim 6, wherein the electrode is lyophilic.   The film forming method according to any one of claims 6 to 8, wherein at least one of the first solution and the second solution is partitioned by a partition wall having liquid repellency. In a film forming method for forming an organic compound layer,
A first coating step of coating a first solution containing an organic compound and a solvent on the electrode;
An evaporation step of evaporating the solvent;
A second application step of further applying a second solution containing the organic compound on the electrode after the solvent has evaporated;
A film forming method comprising:   The film forming method according to claim 10, wherein in the first application step, the first solution is applied to the entire exposed portion of the electrode.   The film formation method according to claim 10, wherein the electrode is lyophilic.   13. The film forming method according to claim 10, wherein at least one of the first solution and the second solution is partitioned by a partition wall having liquid repellency.   An organic compound layer formed by the film forming method according to claim 1.   A film forming method, wherein a liquid repellent conductive layer is selectively coated on a conductive partition.   The film forming method according to claim 15, wherein the liquid repellent conductive layer is a triazyl compound.   The film forming method according to claim 15, wherein the partition wall is a partition wall that partitions a charge transporting solution to be a charge transport layer.   The film forming method according to claim 15, wherein the partition is a voltage line for applying a voltage to one electrode of the organic EL element.   The film forming method according to claim 18, wherein the one electrode is a transparent electrode. A liquid repellent conductive layer;
A partition wall coated with the liquid repellent conductive layer;
An organic EL device comprising a charge transport layer disposed between the partition walls;
A display panel comprising:   The display panel according to claim 20, wherein the barrier rib is a conductor.   The display panel according to claim 20 or 21, wherein the liquid repellent conductive layer is a triazyl compound.   The display panel according to any one of claims 20 to 22, wherein the partition wall is a partition wall for partitioning a charge transporting solution serving as a charge transport layer.   The display panel according to any one of claims 20 to 23, wherein the partition wall is a voltage line for applying a voltage to one electrode of the organic EL element.   The display panel according to claim 24, wherein the one electrode is a transparent electrode.

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