JP2010176868A - Manufacturing method of organic el element, and organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic EL element including an auxiliary electrode that suppresses the occurrence of peeling-off or cracking. <P>SOLUTION: The manufacturing method of the organic EL element includes a step of forming each groove 11a in the surface of an insulating substrate 11, a step in which a conductive paste is coated on the surface of the insulating substrate 11 so as to fill the conductive paste into each groove 11a, a step of forming an auxiliary electrode 12 whose surface is substantially on the same plane as the surface of the insulating substrate 11 by firing the insulating substrate 11, a step of forming a first electrode 13a on the auxiliary electrode 12, a step of forming an organic layer 13b on the first electrode 13a, and a step of forming a second electrode 13c on the organic layer 13b. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an organic EL used for backlight light sources such as liquid crystal televisions and illumination.
(Organic Light Emitting Diode, OLED) It is related with the manufacturing method of an element, and an organic EL element.

  Conventionally, an organic EL element having a large area is known. However, since the transparent electrode used in the organic EL element has a high sheet resistance, the luminance differs greatly between the center and the end of the organic EL element due to a voltage drop. As a result, light emission characteristics such as uniformity are deteriorated. In order to avoid this phenomenon, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-108029 (hereinafter referred to as Patent Document 1), an attempt is made to form a groove in a substrate of an organic EL element and form an auxiliary electrode in the groove by a sputtering method. Has been made.

JP 2003-108029 A

  However, it has been found that it is difficult to produce an organic EL element having an auxiliary electrode by the conventional manufacturing method. This is because it takes a lot of time to produce an auxiliary electrode having a film thickness of micrometer by sputtering. In addition, the organic EL element in which the auxiliary electrode is manufactured by the sputtering method has high internal stress, and the element may peel off or crack.

  The objective of this invention is providing the manufacturing method of the organic EL element which has an auxiliary electrode easily.

  The organic EL device manufacturing method according to the present invention includes a step of forming a groove on a surface of an insulating substrate, a step of applying a conductive paste on the surface of the insulating substrate, and filling the conductive paste in the groove, and the insulating Firing the substrate to form an auxiliary electrode whose surface is substantially flush with the surface of the insulating substrate; forming the first electrode on the auxiliary electrode; and the first electrode A step of forming an organic layer on the substrate, and a step of forming a second electrode on the organic layer.

  The organic EL device according to the present invention includes an insulating substrate having a groove formed on a surface thereof, and a surface roughness formed in the groove so that the surface thereof is substantially flush with the surface of the insulating substrate. An auxiliary electrode having a thickness Ra of 10 nm or less, a first electrode formed on the insulating substrate and the auxiliary electrode, an organic layer formed on the first electrode, and formed on the organic layer The second electrode is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the organic EL element which has an auxiliary electrode can be provided easily. In addition, an organic EL element having an auxiliary electrode can be easily provided.

The perspective view of the organic EL element which shows the 1st Embodiment of this invention. Sectional drawing of the dashed-dotted line A-A 'of FIG. Explanatory drawing which shows the insulated substrate formation process of the 1st Embodiment of this invention. Explanatory drawing which shows the manufacturing process of the organic EL element of the 1st Embodiment of this invention. Explanatory drawing which shows the manufacturing process of the organic EL element of the 2nd Embodiment of this invention. Explanatory drawing which shows the manufacturing process of the organic EL element of the 3rd Embodiment of this invention.

(First embodiment)
FIG. 1 is a perspective view showing a first embodiment of the present invention. 2 is a cross-sectional view taken along one-dot chain line AA ′ shown in FIG.

  In the organic EL element 1, an auxiliary electrode 12 is formed in a groove 11 a formed on the surface of the insulating substrate 11, and an organic EL layer 13 is formed on the auxiliary electrode 12. The auxiliary electrode 12 is formed so as to fill the groove 11 a, and the surface of the auxiliary electrode 12 is formed to be substantially flush with the surface of the insulating substrate 11.

  The insulating substrate 11 has grooves 11a formed in a lattice shape, and the material thereof is, for example, a translucent glass plate.

  The auxiliary electrode 12 improves the light emission characteristics of the organic EL element 1 by lowering the sheet resistance value of a first electrode 13a described later in the organic EL layer 13. The auxiliary electrode 12 is formed, for example, in a lattice shape, and is formed by applying a conductive paste to the groove 11 a provided in the insulating substrate 11. This conductive paste is, for example, a paste composed of 70 to 80 wt% of metal, and the metal is, for example, silver. The conductive paste preferably has a viscosity of 100 to 200 Pa · s. If the viscosity is less than 100 Pa · s, the film is not formed because there is no viscosity. If the viscosity is more than 200 Pa · s, the viscosity is too high and the conductive paste cannot be dropped at a desired position.

  The organic EL layer 13 includes a first electrode 13a, an organic layer 13b, a second electrode 13c, a sealing layer 13, and the like.

  The first electrode 13a provides holes to the organic layer 13b described later. The 1st electrode 13a is comprised with the transparent electrode, for example, is ITO. The first electrode 13a is formed by a sputtering method. The first electrode 13a is formed on the insulating substrate 11 on which the auxiliary electrode 12 is formed so as to be electrically connected to the outside of the organic EL element 1 and the auxiliary electrode 12 as shown in FIG.

  The organic layer 13b emits light when an electric field is generated from the first electrode 13a and a second electrode 13c described later. The organic layer 13b is formed by vapor-depositing an organic substance, and is made of an organic substance such as αNPD or Alq3.

  The second electrode 13c provides electrons to the organic layer 13b. The second electrode 13c is conductive, and is preferably a substance that reflects in order to efficiently emit light when the organic layer 13b emits light, and is made of, for example, aluminum. The second electrode 13c is formed on the organic layer 13b by vacuum deposition so as to be electrically connected to the outside of the organic EL element 1 as shown in FIG.

  The sealing layer 13d is provided to protect the first electrode 13a, the organic layer 13b, and the second electrode 13c from exposure to moisture and oxygen from the outside air and to hermetically seal them. The sealing layer 13d is formed of a sealing can such as glass or stainless steel. The sealing layer 13d is preferably configured so that the first electrode 13a and the second electrode 13c are electrically connected to the outside of the organic EL element 1.

  Here, the auxiliary electrode 12 will be described in more detail.

  The surface roughness Ra of the auxiliary electrode 12 is desirably 10 nm or less. This is because the first electrode 13a, the organic layer 13b, and the second electrode 13c formed on the auxiliary electrode 12 have a thickness of 10 to 100 nm. When the surface roughness Ra of the auxiliary electrode 12 is larger than 10 nm, the unevenness of the surface of the auxiliary electrode 12 becomes larger than the film thickness of the first electrode 13a, the organic layer 13b, and the second electrode 13c, and is emitted from the organic layer 13b. The brightness of the light emitted to the outside of the organic EL element 1 is uneven.

  The auxiliary electrode 12 desirably has a property of reflecting light, and specifically has a reflectance of 90% or more. This is to improve the optical characteristics of the material used for the organic EL element 1, specifically, the light extraction efficiency.

  Among the materials used for the organic EL element 1, there are differences in refractive index between the first electrode 13a and the insulating substrate 11, and between the insulating substrate 11 and the outside of the organic EL element 1. This is because the incident angle at the material interface increases every time light emitted from the organic layer 13b passes through a material having a refractive index different from that of the first electrode 13a and the insulating substrate 11. Light having an increased incident angle, that is, light having an acute angle with respect to the interface is totally reflected at the interface of the substance, so that the light stays in the organic EL element 1 and a light beam can be extracted outside the organic EL element 1. Disappear. As a result, the light emission efficiency of the organic EL element 1 is lowered. Therefore, the auxiliary electrode 12 reflects the light beam, so that the incident angle of light having a large incident angle can be reduced, that is, the light can be made more perpendicular to the material interface, so that total reflection is suppressed. As a result, the light extraction efficiency of the organic EL element 1 itself can be increased.

  The resistivity of the auxiliary electrode 12 is preferably equal to the resistivity of the second electrode 12c, and specifically, it may be 3 μΩ · cm or less. The reason is that if the resistivity of the auxiliary electrode 12 is larger than the resistivity of the second electrode 12 c, an electromotive force is generated in the auxiliary electrode 12, resulting in a power loss and a decrease in the light emission intensity of the organic EL element 1. Because.

  Here, the method for forming the organic EL element will be described in more detail with reference to FIGS. FIG. 3 shows a step of forming the groove 11 a in the insulating substrate 11, and FIG. 4 shows a step of forming the organic EL element 1 having the auxiliary electrode 12.

  As shown in FIG. 3B, the resist 2 is applied to the light-transmitting insulating substrate 11 shown in FIG. Next, as illustrated in FIG. 3C, the exposed portion 2 a is formed by exposing the position where the groove 11 a is formed with a width W. Next, after removing the exposed portion 2a, as shown in FIG. 3 (d), the resist 2 is used as a mask and etched to a desired depth D with hydrofluoric acid to form a groove 11a. Thereafter, the resist 2 is removed to obtain the insulating substrate 11 having the grooves 11a as shown in FIG. Here, the dimensions of D and W are, for example, D: 3 to 5 μm and W: 50 μm. Further, the surface roughness Ra of the groove 11a is desirably 1 μm or less.

  After the groove 11a is formed, the conductive paste having the same volume as the groove 11a is dropped onto the insulating substrate 11 having the groove 11a by, for example, a dispenser, so that the conductive paste is formed in the groove 11a as shown in FIG. To print. Thereafter, the insulating substrate 11 is irradiated with ultrasonic waves, for example, so that the groove 11a is filled with a conductive paste without gaps, and baked, whereby the auxiliary electrode 12 is formed as shown in FIG.

  Next, as shown in FIG. 4C, a film is formed by a sputtering method so that the first electrode 13 a is electrically connected to the auxiliary electrode 12. Next, as shown in FIG. 4D, the organic layer 13b, then the second electrode 13c as shown in FIG. 4E, and the sealing film 13d as shown in FIG. A film is formed by vapor deposition. Thereby, the organic EL element 1 having the auxiliary electrode 12 is formed.

  Here, Patent Document 1 describes that when forming the auxiliary electrode, the auxiliary electrode is formed by using a sputtering method. However, in the manufacturing method of Patent Document 1, it takes a lot of time to manufacture an auxiliary electrode having a film thickness of a micrometer unit. Further, when the auxiliary electrode is manufactured by the sputtering method, the internal stress of the organic EL element becomes strong, and the organic EL element is peeled off or cracked.

  Further, in the sputtering method, it is not possible to form a film only with respect to the groove of the substrate, and the target material that is the source of the auxiliary electrode is scattered to the entire substrate and further to the outside of the substrate, so that the use efficiency of the target material is poor. In addition, a large amount of auxiliary electrodes that are unnecessary after the formation of the auxiliary electrodes are generated, and a process for removing unnecessary auxiliary electrodes is required, which requires extra manufacturing time.

  Further, when the substrate is enlarged, it becomes more difficult to manufacture the auxiliary electrode by the sputtering method. This is because when the substrate is enlarged, the sputtering apparatus for manufacturing the auxiliary electrode must be enlarged, and the mechanism for maintaining the vacuum degree of the processing chamber for performing sputtering becomes complicated, resulting in an increase in running cost. Because. Therefore, it is difficult to use the sputtering method when forming the auxiliary electrode.

  However, according to the above method, when the auxiliary electrode 12 is formed by applying a conductive paste, the dimensions of the auxiliary electrode 12 can be easily controlled by changing the application conditions. In addition, since the conductor is not formed as a particle but is formed in accordance with the shape of the groove 11a, there is no gap unlike the case where it is formed by the sputtering method, so that the internal stress derived from the auxiliary electrode generated inside the organic EL element Can be reduced. Therefore, it is possible to suppress peeling and cracking of the organic EL element.

  Further, in the above method, since the conductive paste can be applied only to the groove of the substrate, the use efficiency of the conductive paste is markedly improved compared to the sputtering method. In addition, since unnecessary auxiliary electrodes are hardly generated, the step of removing unnecessary auxiliary electrodes can be eliminated.

  Furthermore, even if the substrate is enlarged, the above method can easily cope with it. This is because, in the above method, only the mechanism for applying the conductive paste needs to be enlarged, so that the mechanism of the apparatus is not complicated as in the sputtering method, and as a result, an increase in running cost can be suppressed. .

  Therefore, with the above method, it is possible to easily obtain an organic EL element having an auxiliary electrode.

(Second Embodiment)
FIG. 5 is a diagram showing a method for manufacturing an organic EL element according to the second embodiment of the present invention. In the figure, the same components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, as shown in FIG. 5A, the auxiliary electrode 12 is formed by dropping and baking a larger amount of conductive paste than the capacity of the groove 11a with a dispenser, for example. Next, only the surface of the auxiliary electrode 12 is polished to obtain the insulating substrate 11 on which the auxiliary electrode 12 is formed, as shown in FIG. Thereafter, the organic EL element 1 having the auxiliary electrode 12 can be obtained in the same manner as in the first embodiment.

  Therefore, the present embodiment can provide the same effects as those of the first embodiment.

  Further, according to the present embodiment, the polishing of the auxiliary electrode 12 can be realized in a short time. This is because by polishing only the surface of the insulating substrate 11 on which the auxiliary electrode 12 is formed, it is not necessary to polish the surface of the insulating substrate 11 on which the auxiliary electrode 12 is not formed.

(Third embodiment)
FIG. 6 is a diagram showing a method for manufacturing an organic EL element according to the third embodiment of the present invention. In the figure, the same components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof is omitted.

  In this embodiment, as shown in FIG. 6A, a large amount of conductive paste is printed and baked in a desired range of the surface on which the groove 11a of the insulating substrate 11 is formed, for example, by screen printing. Electrode 12 is formed. Next, the surface of the insulating substrate 11 is polished to obtain the insulating substrate 11 on which the auxiliary electrode 12 is formed as shown in FIG. Thereafter, the organic EL element 1 having the auxiliary electrode 12 can be obtained in the same manner as in the first embodiment.

  Therefore, the present embodiment can provide the same effects as those of the first embodiment.

  In the present embodiment, the step of polishing the surface of the insulating substrate 11 in the step of forming the insulating substrate 11 in advance can be omitted. This is because, as described above, when the auxiliary electrode 12 is polished, the insulating substrate 11 is also polished.

  In addition, this invention is not limited to the said structure, For example, you may be as follows.

  In order to improve the adhesion between the insulating substrate 11 and the auxiliary electrode 12, a metal such as palladium may be formed in the groove 11a.

  Further, a desiccant may be sealed inside the sealing film 13d.

  Moreover, the board | substrate formation process which has the groove | channel 11a is not limited above. For example, it is good also as a board | substrate formation process which forms the groove | channel 11a by cutting.

  Moreover, the pattern of the groove | channel 11a is not limited to a grid | lattice form, For example, it may be a wavy line or a straight line, and the arbitrary shapes which combined those two or more may be sufficient.

  Moreover, the shape of the groove | channel 11a is not limited, For example, a semi-elliptical shape and a polygonal shape may be sufficient, and the arbitrary shapes which combined those two or more may be sufficient.

DESCRIPTION OF SYMBOLS 1 Organic EL element 11 Insulating substrate 12 Auxiliary electrode 13 Organic EL layer 13a First electrode 13b Organic layer 13c Second electrode 13d Sealing layer 2 Resist

Claims (2)

Forming a groove on the surface of the insulating substrate;
Applying a conductive paste to the surface of the insulating substrate and filling the conductive paste in the groove;
Firing the insulating substrate to form an auxiliary electrode whose surface is substantially flush with the surface of the insulating substrate;
Forming a first electrode on the auxiliary electrode;
Forming an organic layer on the first electrode;
And a step of forming a second electrode on the organic layer. An insulating substrate having grooves formed on the surface;
An auxiliary electrode having a surface roughness Ra of 10 nm or less, formed in the groove so that the surface thereof is substantially flush with the surface of the insulating substrate;
A first electrode formed on the insulating substrate and the auxiliary electrode;
An organic layer formed on the first electrode;
An organic EL device comprising: a second electrode formed on the organic layer.

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