JP2009043502A - Method of repairing defective portion in organic electroluminescent panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently carry out repair of defective pixels due to particles or the like without damaging a protective film, in an organic EL panel of a film-sealing structure. <P>SOLUTION: Red, green, and blue light-emitting pixels are formed by organic layers 106 separated by pixel separation films 105 on a glass substrate 101 with a first electrode 104 formed, on which, a second electrode 107 and a protective layer 108 are laminated. Defective parts (non-lit pixels) due to particles or the like of the organic EL panel are detected, on which laser light is irradiated to repair the defects. Here, intensity of the laser light is changed for each emission color for controlling to make it an optimum value to prevent the protective layer 108 from damage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for repairing a defective portion of an organic EL panel for improving the yield of the organic EL panel in the manufacturing process of the organic EL panel.

  The organic EL panel is a self-luminous display device, and can have a wider viewing angle, a higher response speed, and a thinner thickness than a non-self-luminous liquid crystal display. Therefore, in recent years, it has attracted attention as a change to a CRT display or a liquid crystal display and has been partially put into practical use.

  The film configuration of a general organic EL element is basically a laminate of an anode, a laminated organic layer made of an organic compound, and a cathode. A transparent anode is formed on a substrate using a glass plate or the like to emit light on the substrate side. It has been taken out of. The light emission of the laminated organic layer is designed to emit a predetermined spectrum, and colorization is realized.

  By the way, it is known that the organic EL element has no resistance to moisture as a problem in the characteristics of the organic EL panel. That is, the organic material used for the organic EL is easily decomposed or deteriorated with respect to moisture, and problems such as a decrease in luminance near dark spots or pixel edges, and a decrease in luminance when stored at high temperatures occur.

  As a moisture blocking technique for the organic EL element, there are a technique for forming a sealing space with glass or metal, and a film sealing technique for sealing with a protective film having low moisture permeability. The former technique has a problem in that it is difficult to reduce the thickness of the panel because the hygroscopic agent is contained in the sealing space formed of glass or metal, so that the sealing space becomes thick. On the other hand, the latter film sealing technique does not require a hygroscopic agent for sealing with a low moisture-permeable protective film, and is a very effective moisture blocking technique from the viewpoint of thinning the panel.

  Furthermore, it is known that organic EL elements are vulnerable to structural defects caused by particles. The laminated organic layer that substantially separates the anode and the cathode of the organic EL element is as thin as about several hundreds of nanometers. Therefore, if there is a structural defect such as a particle between the anode and the cathode, the organic EL element is short-circuited due to electric field concentration. Will occur. In order to avoid this structural defect, it is necessary to reduce and manage particles below the micrometer. However, since it is extremely difficult to eliminate such a small structural defect with the current technology, a defect repair method is expected from the viewpoint of improving the yield of the organic EL panel.

  As a method for repairing the defective part, non-lighting is performed by irradiating the short circuit part between the anode and the cathode of the non-lighting pixel by irradiating the organic layer and the electrode including the particles by irradiating the YAG laser etc. A proposal has been made to restore a pixel to a lit pixel (see Patent Document 1).

  The technique disclosed in Patent Document 1 is an effective means in the sealed space forming technique, and can repair a defective portion without damaging the sealed space.

JP 2000-208252 A

  On the other hand, in the film sealing technique, when a defective portion is irradiated with a YAG laser or the like with an output that causes the electrode to be burned out as in Patent Document 1, film breakage occurs in the protective film for preventing moisture, resulting in a moisture blocking function. Is lost and dark spots occur.

  The present invention has been made in view of such points, and a defective portion of an organic EL panel capable of efficiently repairing a non-lighting pixel (defective portion) of an organic EL panel having a film sealing structure by a protective film. The object is to provide a repair method.

  According to another aspect of the present invention, there is provided a method for repairing a defective portion of an organic EL panel, wherein the defect portion repairing method for an organic EL panel includes an organic layer that forms a plurality of light emitting color pixels. It has the process of irradiating the light of the intensity | strength controlled for every luminescent color.

  Damage to the protective film by irradiating non-lighting pixels (defects) of an organic EL panel having a film sealing structure with a protective film by changing the intensity of the repairing light for each emission color It is possible to turn a non-lighted pixel into a lighted pixel.

  As a result, the production yield of the organic EL panel having a film sealing structure can be greatly improved.

  The defect repairing method of an organic EL panel according to the present invention is characterized in that the intensity of light for repairing a pixel is changed for each emission color of a plurality of emission color pixels. That is, the non-lighting pixel defect portion of each emission color is irradiated with repairing light with an optimum intensity for opening the short-circuit portion between the cathode and the anode. As a result, the defective portion of the organic EL panel can be repaired without damaging the protective film.

  If the intensity of light is the same for each emission color defect, the short circuit between the cathode and the anode may not be opened depending on the emission color. Alternatively, the protective film may be damaged as well as being opened. That is, the light intensity for repairing the defective portion of the organic EL panel having the film sealing structure needs to be finely controlled for each emission color.

  Further, when changing the light intensity corresponding to each light emitting color pixel, the total film thickness t1, t2, t3... Of the organic layer of each light emitting color pixel and the light intensity ratio P1, It is preferable that P2, P3,... Satisfy the following formula (1).

t1: t2: t3 ... = P1: P2: P3 (1)
As the repairing light, light having a wavelength in the visible region or more, for example, generally used laser light may be used. A YAG laser is preferable.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  1 to 3 illustrate a method for repairing a defective portion of an organic EL panel according to Example 1, and FIG. 1 is a schematic diagram illustrating a configuration of an organic EL element. As shown in FIG. 1, a transistor 102 for driving an organic EL element is formed on a glass substrate 101 which is an active matrix substrate, and acrylic resin is spun as a planarizing film 103 for planarizing the undulation of the transistor 102. Covered with a coat. Directly thereon, Cr was deposited as a first electrode 104 by 70 nm and DC magnetron sputtering, and a polyimide resin as a pixel separation film 105 was further coated thereon by spin coating. These films are patterned in each step at any time by contact holes, separation between the first electrodes 104, and the like by a normal photolithography method. At this time, the formed pattern has a pixel number of 160 × 120 dots and a pixel pitch of 0.25 × 0.25 mm.

  In this example, in order to clarify the effect of the present invention, standard particles having a diameter of 0.5 μm were dispersed on the surface of the first electrode 104 assuming particles.

  As the glass substrate 101, an active matrix substrate having 160 × 120 pixels (delta arrangement) and a pixel pitch of 0.25 × 0.25 mm was used.

  After the above steps, dehydration treatment was performed in a vacuum high-temperature furnace. The dehydration conditions were 10 Pa under reduced pressure and a furnace temperature of 200 ° C. for a treatment time of 0.5 to 3 hours. Next, ultraviolet light was irradiated for about 10 minutes in a dry air atmosphere.

  Furthermore, the created active matrix substrate is moved to a vacuum layer, and an organic EL element is produced as follows.

  An organic layer 106 including a hole injection layer, a light emitting layer, an electron transport layer, and an electron injection layer was formed by a resistance heating vapor deposition method. Table 1 in FIG. 4 shows the film thicknesses of the organic layers of the red light emitting pixel, the green light emitting pixel, and the blue light emitting pixel at this time. Only the light emitting layer changes the film thickness, and the structure shown in Table 1 is adopted in consideration of the light extraction efficiency. Subsequently, ITO was deposited to a thickness of 70 nm as the second electrode 107 by DC magnetron sputtering. Next, 3 μm of SiNx was formed as a protective layer (protective film) 108 for preventing moisture on the element by chemical vapor deposition (CVD). The organic EL panel of Example 1 was produced through such steps.

  The organic EL panel of Example 1 is a top emission type organic EL panel whose light extraction direction is opposite to the glass surface.

  The organic EL panel produced in this way was driven, the lighting state was confirmed, and non-lighting pixels were observed in detail. The number of non-lighted pixels generated by the standard particles having a diameter of 0.5 μm dispersed on the surface of the first electrode 104 serving as a short-circuit portion was about 1000 pixels.

  Next, the organic EL panel was moved to the defect repair apparatus shown in FIG. 2, and a defect repair process using a laser beam was performed. This defect repair apparatus includes a laser oscillator 202, a laser optical system 203, a stage 204, and a panel drive system 205, and an enlarged image of a pixel can be confirmed by another monitor 207 via a CCD camera 206 associated with the laser optical system. . The laser oscillator 202 manufactured by HOYA, YAG laser wavelength 1064 nm and 532 nm variable, maximum output 20 mJ, 1 pulse 6 nsec was used. The output is controlled to 200 divisions by a dial. In addition, a ½ filter (not shown) for attenuating the laser can be inserted to suppress excessive energy incidence, and the irradiation area of the laser beam can be reduced by an aperture (not shown). The laser optical system has an objective lens 208 and an imaging lens (not shown), and has a mechanism that enables laser irradiation while visually recognizing an enlarged image of a defective portion via the CCD camera 206.

  In the processing procedure, the organic EL panel is mounted on the stage 204 so that the surface is on the surface, and the stage is coarsely moved so that the objective lens 208 is positioned on the non-lighted pixels. Using the monitor 207, the stage is further finely adjusted and irradiated so that the laser beam is aimed at a defective portion that seems to be a short-circuit portion of the organic EL panel. At this time, the non-lighted pixel position can be turned on by the panel drive system 205 and confirmed on the monitor while moving the stage 204. It is also possible to record the non-illuminated pixel coordinates in advance by another observation means and coarsely move the stage 204.

  It is possible to confirm that the defective portion is repaired by constantly driving the panel drive system 205 and switching to lighting by laser irradiation on the monitor 207. It is also possible to confirm that the laser is driven after laser irradiation in a non-driven state and switched to lighting during laser irradiation.

  As shown in the graph of FIG. 3, the defect repair rate was confirmed by changing the laser output. The laser output value on the horizontal axis is the dial value on the device, and increased by 2 dial values. The defect repair rate on the vertical axis is the defect repair rate for each laser output dial value, and the number of parameters for each dial value is 50. The wavelength used is 1064 nm. FIG. 3 also shows the defect repair rates of the red, green, and blue light emitting pixels.

  Table 1 in FIG. 4 shows the intensity ratio (optimum laser intensity ratio) of the laser output dial value with the highest defect repair rate in each emission color obtained, with the red light emitting pixel as a reference. As shown in Table 1, the ratio of the film thickness ratio of the total thickness of the organic layers of the respective emission colors and the ratio of the laser output intensity ratio are almost the same, and is well matched with the formula (1). As a consideration of the results, it is considered that the light absorption layer materials of the respective colors have different laser light absorptances but are not dominant, but the heat capacity of the total thickness of the organic layer is dominant.

  Within the dial value range of ± 10% centered on the optimum laser output dial value of each luminescent color, it was within 5% of each maximum defect repair rate. Furthermore, the optimum laser output dial value calculated from the film thickness ratio was within that range. Thus, even if the laser intensity is calculated for the light emitting pixels of other colors based on the film thickness ratio, the results can be sufficiently tolerated, and the defect portion is within ± 10% range with the optimum laser output dial value of each light emitting color as the center value. Can withstand the repair of

  As described above, the organic EL panel prepared in Example 1 was held in a high-temperature furnace for 10 hours under conditions of atmospheric pressure, temperature 60 ° C., and humidity 90%. Thereafter, driving and light emission were performed, and defect repaired portions were observed with a microscope, but no dark spots were generated and grown in any of the portions, and no damage to the protective film was observed. Further, the dial value of the laser output at which damage to the protective film begins to occur is 100 or more, and it can be seen that the laser output intensity of each of the above colors does not cause damage to the protective film, and can sufficiently withstand the product.

  As described above, the intensity ratio of the laser output for each emission color is represented by the total film thickness ratio of the organic layers of each emission color, and well fits equation (1). In addition, by determining the laser output conditions for one color, it is possible to easily calculate the laser output conditions for the other colors. By repairing the defective portion of the organic EL panel under such laser output conditions, a method for producing a high-emission top emission organic EL panel can be realized.

  An active matrix substrate was prepared in the same manner as in Example 1 except that ITO 120 nm was formed by DC sputtering as a material for the first electrode, and standard particles were dispersed on the surface of the first electrode in the same manner as in Example 1. Further, as in Example 1, dehydration treatment and surface treatment with ultraviolet rays were performed.

  Also, the organic layer was formed by resistance heating vapor deposition in the same stacking order as in Example 1, and the film thickness of each layer of each emission color was prepared as shown in Table 2 shown in FIG. Unlike Example 1, the second electrode was formed by depositing Al with a thickness of 100 nm by resistance heating vapor deposition. Next, 3 μm of SiNx was formed by chemical vapor deposition (CVD) as a protective layer for preventing moisture on the device. The organic EL panel of Example 2 was produced according to such a form. The organic EL panel of Example 2 is a bottom emission type organic EL panel whose light extraction direction is extracted from the glass surface.

  Next, the laser output was varied by the same evaluation method as in Example 1, and the defect repair rate in each emission color was confirmed. At this time, unlike Example 1, the laser light was incident from the substrate surface. The optimum laser output dial value and the intensity ratio based on the red light emitting pixel are also shown in Table 2 of FIG. The ratios of the intensity ratios shown in Table 2 and the film thickness ratios of the total film thicknesses of the organic layers of the respective colors almost coincide with each other and are well matched with the formula (1).

  Within the dial value range of ± 10% centered on the optimum laser output dial value of each luminescent color, it was within 5% of each maximum defect repair rate. Furthermore, the optimum laser output dial value calculated from the film thickness ratio was within that range. Thus, even if the laser intensity is calculated for the light emitting pixels of other colors based on the film thickness ratio, the results can be sufficiently tolerated, and the defect portion is within ± 10% range with the optimum laser output dial value of each light emitting color as the center value. Can withstand the repair of

  In addition, the organic EL panel of Example 2 prepared by performing defect repair processing in the same manner as in Example 1 was held in a high-temperature furnace for 10 hours under conditions of atmospheric pressure, 60 ° C., and humidity of 90%. After that, when the defect processing portion was confirmed with a microscope by driving and emitting light, no dark spot was generated in any portion, and the protective film was not damaged.

  As described above, the intensity ratio of the laser output for each emission color is expressed by the total film thickness ratio of the organic layers of each emission color, and is well matched with the formula (1). In addition, by determining the laser output conditions for one color, it is possible to easily calculate the laser output conditions for the other colors. By repairing the defective portion of the organic EL panel under such laser output conditions, a method for manufacturing a high-emission bottom emission organic EL panel can be realized.

(Comparative Example 1)
Table 3 in FIG. 6 shows the defect repair rate when the organic EL panel manufactured under the same conditions as in Example 1 is unified with the optimum laser output dial value of one color and the defect repair process is performed. It can be seen that defect output cannot be repaired with high probability at any output, and that the method of the present invention that varies (controls) the laser output according to the total film thickness ratio of each color organic layer is excellent in repairing defective pixels. ing.

(Comparative Example 2)
Table 4 in FIG. 7 shows the defect repair rate when the organic EL panel manufactured under the same conditions as in Example 2 was unified with the optimum laser output dial value of one color and the defect repair process was performed. It can be seen that defect output cannot be repaired with high probability at any output, and that the method of the present invention that varies (controls) the laser output according to the total film thickness ratio of each color organic layer is excellent in repairing defective pixels. ing.

1 is a schematic cross-sectional view illustrating a configuration of an organic EL panel according to Example 1. FIG. It is a figure which shows a defect repair apparatus. 3 is a graph showing the evaluation results of Example 1. Table 1 shows the film configuration of the organic layer according to Example 1 and the laser intensity ratio for repairing the defective portion. Table 2 shows the film configuration of the organic layer according to Example 2 and the laser intensity ratio for repairing the defective portion. Table 3 shows a defect repair rate of each light emitting color pixel in Comparative Example 1. Table 4 shows a defect repair rate of each light emitting color pixel in Comparative Example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Glass substrate 102 Transistor 103 Flattening film 104 1st electrode 105 Pixel separation film 106 Organic layer 107 2nd electrode 108 Protective layer 202 Laser oscillator 203 Laser optical system 204 Stage 205 Panel drive system 206 CCD camera 207 Monitor

Claims (4)

In the method for repairing a defective portion of an organic EL panel having an organic layer for forming a plurality of light emitting color pixels,
A method for repairing a defect portion of an organic EL panel, comprising: irradiating a defect portion of the organic layer with light having a controlled intensity for each emission color of the plurality of emission color pixels. The total film thickness t1, t2, t3... Of the organic layer of each luminescent color pixel and the intensity ratio P1, P2, P3. 2. The defect repairing method for an organic EL panel according to claim 1, wherein the relationship is satisfied.
t1: t2: t3 ... = P1: P2: P3 ...   3. The method for repairing a defective portion of an organic EL panel according to claim 1, wherein the wavelength of the light is not less than a visible region. Forming an organic EL panel in which a first electrode, an organic layer for forming a plurality of light emitting color pixels, a second electrode and a protective film are laminated on a substrate;
Irradiating the defect portion of the organic layer with light having a controlled intensity for each emission color of the plurality of emission color pixels.

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