JP2008235139A - Aging device of organic el device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aging device of an organic EL device which carries out aging in a short time, and its method. <P>SOLUTION: The aging device 10 of an organic EL device 20 comprises a container 12, liquid 14 which is filled in a container 12 and in which the organic EL device 20 is immersed, connectors 16a, 16b to be connected respectively to a first electrode 32 and a second electrode 34, and a power source 18 which flows electric current to an organic light-emitting layer 26 through the first electrode 32 and the second electrode 34 from the connectors 16a, 16b and to make it emit light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aging device for an organic EL device and a method thereof, which can finish aging in the production of an organic EL device in a short time.

  Organic EL devices have attracted attention (Non-Patent Document 1). In the organic EL device, an anode, an organic light emitting layer, and a cathode are sequentially laminated on a transparent substrate, and these are sealed with a cap. When a voltage is applied to the organic light emitting layer between the anode and the cathode, the organic light emitting layer emits light. In order to assist the movement of electrons and holes, it is common to provide an electron transport layer between the cathode and the organic light emitting layer, or to provide a hole transport layer between the anode and the organic light emitting layer.

The luminance of the organic EL device deteriorates with time. The relationship between luminance and time of a general organic EL device is as shown in FIG. From the figure, it can be seen that the initial luminance degradation is severe, and the pace of degradation is considerably slow after a certain period of time. In general, the time when the luminance is halved is referred to as the luminance half time. When the brightness is halved, it is determined that the product has reached the end of its service life. Accordingly, the time condition at the time when shipping the organic EL device T ₁ of the 0 in FIG. 11 is a life of the product. The brightness is less likely to deteriorate when shipped in time T ₂ after the state, the life of the product is prolonged. For this reason, in the manufacture of the organic EL device, there is a process called aging in which the luminance is deteriorated by turning on the organic EL device.

  In order not to lower the production efficiency, it is preferable to finish aging in as short a time as possible. Aging is performed by increasing the current density of the organic light emitting layer in a thermostatic chamber whose temperature is increased. Due to the high current density, the brightness during aging is high. By performing aging under conditions that are harsher than in normal use, luminance degradation is promoted. Patent Document 1 discloses aging for increasing current density.

  However, the aging disclosed in Patent Document 1 takes at least 4 hours or more. Since the next process cannot be performed while aging is performed, the organic EL device is kept in the aging device for 4 hours. This is an obstacle to mass production of organic EL devices.

  Further, the temperature of the organic light emitting layer is increased in order to increase the current density of the organic light emitting layer in the thermostat. If the temperature of the organic light emitting layer is raised too much, the organic light emitting layer is broken. In order to finish aging in a short time, the temperature in the tank cannot be raised too much, or the current density cannot be raised too much. When the temperature of the organic light emitting layer rises in part due to a bias in the current density of the organic light emitting layer, only that part is destroyed.

  When the temperature in the thermostatic chamber is increased or the current density is increased in order to accelerate aging, the temperature of the organic light-emitting layer is not uniform because the atmosphere is in the atmosphere, and a portion where the temperature is locally increased appears. In the organic light emitting layer, current flows easily when the temperature rises, and current concentration occurs in that portion. Once the temperature has risen, the temperature is accelerated and the organic light emitting layer is broken. As described above, even if the aging in the air atmosphere is finished in a short time, the temperature in the thermostatic chamber or the current density cannot be increased so much.

Japanese Patent Laid-Open No. 8-185979 Nikkei Electronics February 26, 2007 issue (no. 946) p10 Published by Nikkei BP

  An object of the present invention is to provide an aging device for an organic EL device and a method for preventing the destruction of the organic EL device and performing aging in a short time.

  An aging device of the present invention includes a transparent substrate having one surface and another surface, a laminate including an anode, an organic light emitting layer, and a cathode laminated on one surface of the transparent substrate, the anode, the organic light emitting layer, And a member for sealing the cathode with the transparent substrate, a first electrode connected to the anode from the outside of the member for sealing with the transparent substrate, and the outside of the member for sealing with the transparent substrate. An organic EL device manufacturing apparatus, comprising: a second electrode connected to a cathode; a container; a liquid that is placed in the container and into which the organic EL device is immersed; the first electrode; A connector connected to each of the two electrodes; and a power source that emits light by causing a current to flow from the connector to the organic light emitting layer through the first electrode and the second electrode.

  The aging method using the aging device includes a step of preparing a container in which a liquid is placed, a step of immersing the organic EL device in a liquid in the container, the first electrode and the second electrode. Connecting each of the electrodes to the electrode, and causing a current to flow from the power source to the organic light emitting layer via the connector and the first electrode and the second electrode to emit light.

  According to the present invention, the local temperature rise of the organic EL device can be prevented by performing aging by immersing the organic EL device in a liquid as compared with the case where it is performed in the air. Therefore, the liquid temperature can be made higher than normal temperature (about 25 ° C.) or a current higher than the rated current can be passed through the organic light emitting layer, and aging can be completed in a short time. Moreover, since the temperature rise of the organic EL device can be prevented by lowering the liquid temperature below room temperature, it can be kept at a desired temperature. The temperature condition of aging can be adjusted, and destruction of the organic light emitting layer can be prevented.

  Embodiments of an aging apparatus and method for an organic EL device according to the present invention will be described with reference to the drawings.

  The organic EL device 20 to be aged is shown in FIGS. In the organic EL device 20, a transparent electrode (anode) 24, an organic light emitting layer 26, and a metal electrode (cathode) 28 are sequentially laminated on a transparent substrate 22 such as glass. The organic light emitting layer 26 is sealed so as not to come into contact with oxygen. The sealing member is a cap 30 made of glass or metal. The substrate 22 and the cap 30 are bonded. In general, a hole transport layer is provided between the transparent electrode 24 and the organic light emitting layer 26, and an electron injection layer is provided between the organic light emitting layer 26 and the metal electrode 28 to increase the light emission efficiency. Light emitted from the organic light emitting layer 26 is emitted to the outside through the transparent substrate 22. Also, the cathode 28 and the cap 30 made of metal reflect light and direct the light toward the transparent substrate 22. Such a structure is called a bottom emission structure.

  The first electrode 32 is connected to the anode 24 from the outside. Further, the second electrode 34 is connected to the cathode 28 from the outside. These electrodes 32 and 34 are sandwiched between the transparent substrate 22 and the cap 30 when entering from the outside to the inside of the organic EL device 20. In FIG. 3B, the cathode 28 is in contact with the side surfaces of the anode 24 and the organic light emitting layer 26, but is actually insulated.

  A space 36 is formed between the cap 30 and the cathode 28. This space 36 is filled with an inert gas such as nitrogen. The transparent substrate 22 and the cap 30 are bonded with an adhesive, and the organic light emitting layer 26 and the like are sealed. Further, the electrodes 32 and 34 are also prevented from having a gap. A desiccant is attached to the inner surface of the cap 30. This is because the organic light emitting layer 26 is not deteriorated by moisture. For convenience of explanation, the number of the organic light emitting layers 26 is one, but they may be divided vertically and horizontally.

  Only the brightness of the organic light emitting layer 26 is different before and after aging. There is no change in the configuration of the organic EL device 20. The material and structure of the organic EL device 20 are designed so as to obtain a desired luminance by aging.

  The present invention is an aging device of the organic EL device 20 described above. As shown in FIG. 1, the configuration of the device 10 includes a container 12, a liquid 14 that is placed in the container 12 and in which the organic EL device 20 is immersed, and each of the first electrode 32 and the second electrode 34. Connectors 16a and 16b to be connected, and a power source 18 that emits light by flowing current from the connectors 16a and 16b to the organic light emitting layer 26 through the first electrode 32 and the second electrode 34 are included.

  The organic EL device 20 emits light in the liquid 14 and generates heat. Therefore, the size of the container 12 and the amount of the liquid 14 are appropriately designed according to the size of the organic EL device 20 and the cooling condition of the organic EL device 20. Means for fixing the organic EL device 20 is provided inside the container 12.

  The liquid 14 used is an inert, non-explosive, non-corrosive or insulating liquid. This is because the organic EL device 20 emits light safely. The organic light emitting layer 26 and the like are sealed. Accordingly, it is safe to put the organic EL device 20 in the liquid 14. If the organic light emitting layer 26 is not sealed, it is necessary to select a liquid in which the organic light emitting layer 26 does not deteriorate with moisture or oxygen. Although it is theoretically possible, it is difficult to prepare a liquid from which moisture and oxygen have been completely removed. Even if it is prepared, if water or oxygen enters for some reason during use, the organic light emitting layer 26 is deteriorated. Further, if the organic light emitting layer 26 is not sealed, it is necessary to cover the liquid and the organic light emitting layer 26 with an inert gas. This is because the organic light emitting layer 26 is not deteriorated by oxygen or moisture in the air. It is practically impossible to immerse or move the organic light emitting layer 26 in the liquid without sealing.

  If the liquid 14 is used, the connectors 16a and 16b may be made of copper. This is because the connector 16a and 16b are not corroded with the liquid 14 described above. Since the electrodes 32 and 34 do not have to be corroded by the liquid 14, it is not necessary to apply a corrosion resistance treatment to the liquid 14.

  The direction of the organic EL device 20 in the container 12 is not limited to the direction of FIG. It is preferable to provide a window in the container 12 or to consider the direction of the organic EL device 20 so that the emission luminance can be confirmed. Further, the number of organic EL devices 20 put in the liquid 14 is not limited to one.

  In the present invention, the organic EL device 20 is placed in the liquid 14 for aging. Therefore, even if the temperature of the organic light emitting layer 26 rises, it can be easily cooled by the liquid 14. Since the entire organic EL device 20 is covered with the liquid 14, the cooling effect is high. In particular, the heat of the organic light emitting layer 26 can be removed through the transparent substrate 22. Even if the current density of the organic light emitting layer 26 is increased to increase the luminance, the temperature of the organic light emitting layer 26 is not easily raised, and therefore, it is not easily broken. Since aging can be performed with higher brightness than in air, aging can be completed in a short time. For example, aging is completed in about 10 to 30 minutes.

  It is also conceivable to press a metal plate having a high thermal conductivity against the transparent substrate 22. However, a gap is inevitably formed between the transparent substrate 22 and the metal plate, and the cooling effect is inferior to that of the liquid 14. There is also a drawback that the light emission state cannot be confirmed by the metal plate. In order to confirm the light emission state, it is also conceivable to press a metal plate against the cap 30. However, since there is a space 36 between the cathode 28 and the cap 30, the cooling effect is small. Therefore, it is more effective to use the liquid 14 as in the present application than to use a metal plate for cooling.

As an example, the organic light emitting layer 26 has a current density of about 1.times higher than that when the organic EL device 20 is used as a product in the air (the rated current density for the organic light emitting layer 26 to emit light without being destroyed in the air). It is made to emit light with a high brightness of 2 to 20 times. The current density of the organic light emitting layer 26 is adjusted by the power source 18. The current density is, for example, about 10 to 1000 mA / cm ² . The temperature of the liquid 14 at this time is about 25 ° C. Even when the luminance and current density increase, the temperature of the liquid 14 does not increase so much, and the temperature increase of the organic light emitting layer 26 can be suppressed.

  The liquid 14 is preferably a fluorine-based inert liquid. An example is Galden (trade name) or Florinart (trade name). In addition, since the aging time is short, as long as there is almost no corrosion of the electrodes 32, 34, etc., other liquids may be used. For example, pure water is used. In this case, the connectors 32 and 34 are subjected to corrosion resistance treatment. Further, liquids other than the liquid 14 can be used. In this case, the connectors 32 and 34, the electrodes 32 and 34, and the like are subjected to anti-corrosion treatment for the liquid.

  The present invention may also include means for cooling or heating the liquid 14, means for adjusting the temperature, means for circulating, or at least two of them. For example, as illustrated in FIG. 4, the apparatus 10 b covers the container 12 with another container 40 and is filled with a liquid 42 having high heat conduction between the container 12 and the container 40. As the liquid 42, a liquid having a high thermal conductivity can be used regardless of the corrosion problem of the electrodes 32 and 34. By cooling the liquid 12, the cooling effect of the organic light emitting layer 26 is enhanced. This cooling includes not only lowering the raised liquid temperature but also actively lowering the temperature of the liquid 14 at room temperature. The liquid 42 may be circulated.

  As in the apparatus 10c shown in FIG. 5, a pipe 44 is attached to the container 12, and the liquid 14 is circulated by the pump P in the direction of the arrow. The liquid 14 is cooled while circulating through the pipe 44. The temperature rise of the liquid 14 can always be avoided, and the temperature rise of the organic light emitting layer 26 can be avoided.

  You may make it adjust temperature like the apparatus 10d of FIG. The apparatus 10d attaches the pipe 44 to the container 12 and circulates the liquid 14 with the pump P in the direction of the arrow, like the apparatus 10c. A temperature adjusting means 46 is provided in the middle of the pipe 44. The temperature is adjusted so that the liquid 14 is heated or cooled to a constant temperature by the temperature adjusting means 46. The temperature adjusting means 46 is provided with a heater for heating the liquid 14 or provided with a refrigerant for cooling. Furthermore, a thermometer that measures the temperature of the liquid 14 and a microcomputer that controls the heater and the refrigerant from the value of the thermometer so that the liquid 14 reaches a desired temperature are included. The liquid 14 is adjusted to a desired temperature by directly or indirectly contacting the heater or the refrigerant. For example, the temperature of the liquid 14 is once raised to a temperature suitable for aging, and then kept at that temperature. Or, conversely, after the temperature of the liquid 14 is lowered, the temperature is kept at that temperature. By adjusting the temperature of the liquid 14 to the optimum temperature for aging, the aging time can be shortened.

  Although the apparatus 10d of FIG. 6 was able to perform heating and cooling, only one of them may be used. That is, only the heating means (heater) is operated, or only the cooling means (refrigerant) is operated. Furthermore, only one of the means may be provided. If only the means for heating is used, heating is performed when the liquid temperature is lower than a predetermined temperature, and heating is stopped when the liquid temperature reaches a predetermined temperature. If only the cooling means is used, the cooling is performed if the liquid temperature is higher than a predetermined temperature, and the cooling is stopped when the liquid temperature reaches a predetermined temperature. If the room temperature, liquid temperature, and temperature rise rate of the organic EL device 20 are known in advance when aging is performed, the liquid 14 is heated or cooled at a constant rate so that the desired temperature is obtained. The liquid temperature can also be maintained.

  As shown in FIGS. 5 and 6, the liquid 14 may be circulated (stirred) by providing a blade that rotates in the container 12 without using the pipe 44 or the pump P. By adjusting the temperature of the liquid 14 to provide fluidity, the temperature of the organic light emitting layer 26 can be adjusted, and aging can be performed in a short time. The temperature deviation of the organic light emitting layer 26 can also be prevented, and the temperature can be prevented from being broken only partially. In particular, since the liquid 14 has a higher thermal conductivity than air, the temperature of the organic light emitting layer 26 can be easily adjusted, and temperature deviation can be eliminated.

  In addition, although it demonstrated that the thermometer was used in the apparatus 10d of FIG. 6, it is the same also in other apparatuses 10, 10b, and 10c. A thermometer for measuring the temperature of the liquid 14 may be attached so that the operation of other means can be controlled from the value of the thermometer. For example, when the temperature of the liquid 14 is too high, the power source 18 is stopped or an alarm is sounded by computer control. The circulation speed of the liquid 14 by the pump P may be changed depending on the liquid temperature. In addition, you may combine suitably the apparatus demonstrated in FIG.

Examples will be described below. FIG. 7 shows the relationship between the current voltage flowing through the organic light emitting layer 26 and time. The light emitting area of the organic EL device 20 at this time is 18 mm × 18 mm. The temperature of the liquid 14 at the start of light emission was about 25 ° C. When the current density was 108 mA / cm ² , the temperature of the liquid 14 slightly increased, but the organic light emitting layer 26 was not destroyed. When the current density was 85 mA / cm ² or less, the temperature of the liquid 14 did not increase and the organic light emitting layer 26 emitted light satisfactorily. It was found that even when the current density was 108 mA / cm ² , the organic light emitting layer 26 was cooled by the liquid 14 and light emission could be sustained. In the case of air, the temperature of the organic light emitting layer 26 increases rapidly at about 15 mA / cm ² and is destroyed.

FIG. 8 shows the luminance change after aging. The light emitting area of the organic EL device 20 is 18 mm × 18 mm, the current density during aging is 85 mA / cm ² , and the aging time is 2 hours. The aging was aging soaked in the liquid 14, and the temperature of the liquid 14 was about 25 ° C. After aging, the measured current density of the organic light emitting layer 26 was 8 mA / cm ² and the initial luminance was 754 cd / m ² . From the graph, there is some luminance change, but the luminance is almost stable. It can be seen that aging is completed within 2 hours.

FIG. 9 shows changes in luminance of the organic EL device 20. The light emitting area of the organic EL device 20 was 18 mm × 18 mm, and the current density was 46 mA / cm ² . Aging was performed while the organic EL device 20 was immersed in a liquid at about 25 ° C. The initial light emission luminance was about 8500 cd / m ² , but the deterioration of the luminance progressed considerably until about 20 to 30 minutes, and the luminance became almost stable thereafter. That is, it can be seen that aging is completed in about 20 to 30 minutes. Although the current density is higher than the rated current of the organic EL device 20, the temperature rise is prevented by the liquid 14, and the organic light emitting layer 20 is not destroyed.

  As described above, according to the present invention, aging can be completed in a short time by immersing the organic EL device 20 in the liquid 14 and performing aging. It is much shorter than the aging time described in the prior art. Since the aging time is short, the production efficiency can be improved and the price of the product can be reduced.

  In the above description, the bottom emission type organic EL device 20 has been described. However, a top emission type organic EL device may be used. The transparent substrate 22 of FIGS. 2 and 3 becomes a metal plate, and the cap 30 becomes transparent. The positions of the anode 24 and cathode 28 of the laminate on the substrate 22 change. Moreover, you may use for the aging of the organic electroluminescent apparatus 20b which provided the sealing film 30b so that the cathode 28 etc. which are shown to Fig.10 (a), (b) directly may be covered. Since there is no space 36 unlike the organic EL device 20 of FIG. 3, the organic light emitting layer 26 can be cooled, heated, or adjusted in temperature from the sealing film 30b. The organic EL device 20b using the sealing film 30b may be bottom emission or top emission. Further, the organic EL device may be configured such that light is emitted from both the substrate 22 and the cap 30 (or the sealing film 30b) without using a metal plate or a metal electrode. Thus, the present invention can perform aging of various organic EL devices.

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the gist thereof.

It is a figure which shows the aging apparatus of the organic electroluminescent apparatus of this invention. It is a front view of an organic EL device. FIG. 3 is a cross-sectional view of the organic EL device, where (a) is a cross-sectional view taken along the line XX of FIG. 2, and (b) is a cross-sectional view taken along the line Y-Y of FIG. It is the figure which provided the cooling means of the liquid in the structure of FIG. FIG. 2 is a diagram in which liquid circulation means is provided in the configuration of FIG. 1. FIG. 2 is a diagram in which liquid circulation means and temperature adjustment means are provided in the configuration of FIG. 1. It is a graph which shows the relationship between the voltage of an organic EL device in liquid, and time. It is a graph which shows the relationship between the brightness | luminance of organic EL apparatus after aging, and time. It is a graph which shows the relationship between the brightness | luminance and time of the organic electroluminescent apparatus in a liquid. It is sectional drawing of the organic electroluminescent apparatus which seals an organic light emitting layer with a film | membrane, (a) is XX sectional drawing corresponding to Fig.3 (a), (b) is Y corresponding to FIG.3 (b). FIG. It is a graph which shows the relationship between the brightness | luminance of a general organic EL apparatus, and time.

Explanation of symbols

10: Aging device of organic EL device 12: Container 14: Liquid 16a, 16b: Connector 18: Power source 20: Organic EL device 22: Transparent substrate 24: Transparent electrode 26: Organic light emitting layer 28: Metal electrode 30: Caps 32, 34 : Electrode 36: Space

Claims (7)

A substrate having one side and the other side;
A laminate including an anode, an organic light emitting layer, and a cathode laminated on one surface of the substrate;
A member for sealing the laminate with the substrate;
A first electrode connected to the anode from the outside of the substrate and the member to be sealed;
A second electrode connected to the cathode from the outside of the substrate and the sealing member;
An aging device for an organic EL device including
A container,
A liquid that is placed in the container and into which the organic EL device is immersed;
A connector connected to each of the first electrode and the second electrode;
A power source for causing a current to flow from the connector to the organic light emitting layer through the first electrode and the second electrode to emit light;
Aging device including. The aging device according to claim 1, wherein the organic light emitting layer emits light with higher brightness than when the organic EL device is used as a product in the air. The aging apparatus according to claim 1 or 2, wherein the liquid is a fluorine-based inert liquid or pure water. The aging device according to any one of claims 1 to 3, comprising means for cooling or heating the liquid, means for adjusting the temperature, means for circulating, or at least two of them. A substrate having one side and the other side;
A laminate including an anode, an organic light emitting layer, and a cathode laminated on one surface of the substrate;
A member for sealing the laminate with the substrate;
A first electrode connected to the anode from the outside of the substrate and the member to be sealed;
A second electrode connected to the cathode from the outside of the substrate and the sealing member;
A method for aging an organic EL device comprising:
Preparing a container containing a liquid;
Immersing the organic EL device in a liquid contained in a container;
Connecting a connector to each of the first electrode and the second electrode, and causing a current to flow from the power source to the organic light emitting layer through the connector and the first electrode and the second electrode to emit light, thereby reducing the luminance of the organic light emitting layer When,
Aging method including: 6. The aging method according to claim 5, wherein the light emitting step causes the organic light emitting layer to emit light with higher brightness than when the organic EL device is used as a product in the air. The aging method according to claim 5 or 6, comprising a step of cooling or heating the liquid, a step of adjusting the temperature, a step of circulating, or at least two of them.

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