JP2006049057A - Organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device in which light emitting efficiency is maintained and the prolongation of a lifetime is achieved by suppressing the temperature elevation of an organic multilayered film accompanied by light emission. <P>SOLUTION: By forming a recess 11a to be thin at the rear face of an insulating substrate 11 forming an organic EL light emitting element 15 and by tightly arranging an aluminum plate 31 in the recess 11a with a silicon adhesive 30, the aluminum plate 31 is tightly arranged in close contact with the bottom face of the recess 11a near an exothermic source, so that thermal diffusion is promoted by the aluminum plate 31, and heat radiation efficiency can be enhanced. By this, the light emitting efficiency of an organic light emitting film 13 is not reduced and the prolongation of the lifetime of the organic EL display device can be achieved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic EL display device in which an organic light emitting layer is provided between a pair of electrodes, and an electric field is applied to the organic light emitting layer by the pair of electrodes to emit light, and particularly heat generated in the organic light emitting layer constituting the light emitting region. In particular, the present invention relates to an organic EL display device capable of suppressing a decrease in efficiency of the light emitting region due to a long life and improving reliability.

  In recent years, liquid crystal display devices (LCD), plasma display devices (PDP), field emission display devices (FED), organic EL display devices (OLED), etc. are in the practical application or practical application research stage as flat panel display devices. . Among them, the organic EL display device is a very promising display device as a future display device as a typical thin and lightweight self-luminous display device. Organic EL display devices include a so-called bottom emission type and a top emission type.

  A bottom emission type organic EL display device includes a first electrode or a transparent electrode such as ITO as one electrode on an insulating substrate suitable for a glass substrate, an organic multilayer film that emits light by applying an electric field (organic light emitting layer) In other words, the organic EL light emitting element is configured by a light emitting mechanism in which reflective metal electrodes as the second electrode or the other electrode are sequentially stacked. A large number of organic EL light emitting elements are arranged in a matrix, and another substrate, which is also referred to as a sealing can, is provided to cover the laminated structure, thereby blocking the light emitting structure from the external atmosphere.

  Then, for example, by applying an electric field between the electrodes using the transparent electrode as the anode and the metal electrode as the cathode, carriers (electrons and holes) are injected into the organic multilayer film, and the organic multilayer film emits light. This light emission is emitted from the glass substrate side to the outside.

  On the other hand, in the top emission type organic EL display device, one of the electrodes described above is a reflective metal electrode, and the other electrode is a transparent electrode such as ITO, and an electric field is applied between the two electrodes. The film emits light, and the emitted light is emitted from the other electrode side described above. In the top emission type, a transparent plate suitable for a glass plate is used as a sealing can in the bottom emission type.

In the organic EL display device configured as described above, carriers are injected into the organic multilayer film of the light emitting mechanism in accordance with the electric field applied between one electrode and the other electrode when the organic EL light emitting element emits light, and light is emitted. However, not all of the injected carriers contribute to light emission, and some of the injected carriers generate heat to heat the light emitting mechanism. In general, the material of the organic multilayer film constituting the light emission mechanism is deteriorated in light emission characteristics due to heat generation, and the lifetime is reduced. For this reason, it is necessary to remove heat generation. As a countermeasure against such heat generation, a structure in which a heat radiation effect is improved by attaching a metal heat radiation member having high thermal conductivity to the back surface of a substrate on which an organic multilayer film is formed is described in Patent Document 1 below. ing.
JP 2002-343555 A

  However, in the organic EL display device configured as described above, when a substrate having a low thermal conductivity such as glass is used as the substrate itself, a structure in which a heat dissipation member is simply provided or pasted on the back surface of the substrate is organic. The distance between the multilayer film and the heat radiating member is large, and a sufficient heat radiation effect cannot be expected. As a result, the organic multilayer film constituting the light emitting mechanism is promoted to deteriorate in light emission characteristics due to heat generated during lighting. In addition, this heat generation is a factor that hinders the extension of the life of the organic EL display device.

  Therefore, the present invention has been made to solve the above-described conventional problems, and the object thereof is to maintain the luminous efficiency by suppressing the temperature increase of the organic multilayer film due to such light emission and An object of the present invention is to provide an organic EL display device with a long life.

  In order to achieve such an object, the organic EL display device according to the present invention is provided with a thin concave portion on the back surface of an insulating substrate on which a plurality of organic EL light emitting elements are formed, and a heat dissipation member is disposed in the concave portion. By doing so, since this heat radiating member is arrange | positioned close to the bottom face of the recessed part near a heat generating source, the subject of background art can be solved by accelerating | stimulating the thermal diffusion of a heat radiating member.

  In another organic EL display device according to the present invention, preferably, in the above configuration, the heat radiating member is made of an aluminum plate, so that the aluminum plate is disposed close to the heat source, so that the thermal diffusion of the aluminum plate is promoted. Can solve the problems of the background art.

  In another organic EL display device according to the present invention, preferably, in the configuration described above, the heat dissipation member is a copper plate material, so that the copper plate material is disposed close to the heat source, so that the thermal diffusion of the copper plate material is promoted. This can solve the problems of the background art.

  In another organic EL display device according to the present invention, preferably, in the above configuration, the heat dissipating member is disposed close to the heat source by adhering and disposing the heat dissipating member using a silicon adhesive having high thermal conductivity. The problem of the background art can be solved by promoting the thermal diffusion of the heat dissipation member.

  In another organic EL display device according to the present invention, preferably, in the above configuration, the heat diffusion of the heat radiating member is further promoted by forming fine uneven surfaces on the outer surface and the inner surface of the heat radiating member disposed in the concave portion. As a result, the problems of the background art can be solved.

  In another organic EL display device according to the present invention, preferably, in the above configuration, the heat dissipation member is a metal film, so that the metal film is disposed close to the heat source, so that the thermal diffusion of the metal film is promoted. This can solve the problems of the background art.

  In another organic EL display device according to the present invention, preferably, in the above configuration, the thermal diffusion of the metal film is further promoted by forming a fine uneven surface on the outer surface of the metal film disposed in the recess. This can solve the problems of the background art.

  The present invention is not limited to the configurations described in the above-described configurations and the embodiments described later, and it goes without saying that various modifications can be made without departing from the technical idea of the present invention. .

  According to the organic EL display device of the present invention, a thin concave portion is provided on the back surface of the insulating substrate on which a plurality of organic EL light emitting elements are formed, and the heat radiating member is heated by installing the heat radiating member in the concave portion. Since it is close to the bottom surface of the recess close to the source, it is possible to efficiently diffuse the heat generated in the organic EL light emitting device and to improve the heat radiation efficiency. As a result, the light emission efficiency of the organic EL light emitting element is not lowered, and an extremely excellent effect such that the life of the organic EL display device can be extended is obtained.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings of the examples. Here, a top emission type organic EL display device is taken as an example.

  FIG. 1 is a cross-sectional view of an essential part schematically illustrating the layer structure of an organic EL element according to Example 1 of an organic EL display device according to the present invention. FIG. 2 is a cross-sectional view of an essential part for schematically explaining the overall structure of Example 1 of the organic EL display device according to the present invention. Further, FIG. 3 is a perspective view of a main part viewed from the back of the organic EL display device shown in FIG. In these drawings, only one pixel is shown for ease of explanation, and a switching element for selecting a pixel, a control element for controlling light emission luminance, and the like are mounted, but are omitted here.

  The insulating substrate 11 shown in FIG. 1 is an active matrix substrate (also referred to as a thin film transistor substrate or a TFT substrate) that constitutes an organic EL display device. The insulating substrate 11 is formed from a ceramic plate material or a glass plate material. A cathode 12 as a light emission control electrode is formed on the main surface of the insulating substrate 11 by patterning a conductive metal film for each pixel. As the conductive metal film, an aluminum (Al) layer 12a as a first layer and a lithium fluoride (LiF) layer 12b as a second layer were used from the insulating substrate 11 side. The film thickness of the aluminum layer 12a is, for example, about 200 nm, and the film thickness of the lithium fluoride layer 12b is, for example, about 1 nm.

  In addition, Mg / Al or Mg / In may be used for the conductive metal film. These conductive metal films are formed on the main surface of the insulating substrate 11 by vapor deposition, sputtering, CVD, or the like, patterned to a required size using a photolithography process or the like, and the cathode 12 for each pixel. Form. The cathode 12 preferably has good light reflectivity.

  An organic multilayer film 13 constituting the organic light emitting structure of the organic EL light emitting element is formed on the upper surface of the cathode 12. The organic multilayer film 13 is formed by sequentially laminating an electron transport layer 13a, a light emitting layer 13b, a hole transport layer 13c, and a hole injection layer 13d from the cathode 12 side. The film thickness of the organic multilayer film 13 is about 150 nm, for example.

An example of the material of the organic multilayer film 13 is as follows. That is, Alq ₃ (tris (8-hydroxyquinoline) aluminum) or the like is used for the electron transport layer 13a. For the light emitting layer 13b, a light emitting material using 9,10-diphenylanthracene as a host material and perylene as a dopant material is used. In addition, α-NPD (α-naphthylphenyldiamine) or the like is used for the hole transport layer 13c. The hole injection layer 13d is made of CuPc (copper phthalocyanine) or the like.

  Further, an anode 14 is formed on the upper surface of the organic multilayer film 13 to form an organic EL light emitting element 15. A transparent conductive thin film such as ITO (In—Ti—O) or IZO (In—Zn—O) can be used for the anode 14. Here, for example, an ITO film having a thickness of about 30 nm or less is used. . In the active matrix type, a pixel selection circuit or a pixel driving circuit having a thin film transistor (TFT) formed of LTPS (low temperature polysilicon semiconductor film) or the like is formed on the main surface of the insulating substrate 11. However, illustration is omitted here.

  Further, a gas barrier film 16 is formed on the uppermost layer of the organic EL light emitting element 15 so as to cover the cathode 12, the organic multilayer film 13, and the anode 14. The gas barrier film 16 is formed of a gas non-permeable material layer such as a polymer film, a silicon nitride film, or a silicon oxide film. In particular, the organic multilayer film 13 is protected from adsorption of moisture and gas components in the external atmosphere. Therefore, the deterioration of the light emission characteristics due to this is prevented. Further, after the gas barrier film 16 is formed, a metal film having a high thermal conductivity may be formed on the surface of the gas barrier film 16 (not shown). By forming this metal film, heat generated from the inside due to light emission can be dissipated to the insulating substrate 11, so that the life of the organic multilayer film 13 can be extended. The film thickness of the gas barrier film 16 and the metal film formed in the uppermost layer is about several μm.

  In addition, a desiccant 23 is accommodated on the inner surface of the insulating substrate 11. The desiccant 23 is formed by forming a known desiccant into a sheet shape and affixing the inner surface of the insulating substrate 11, or in a gel form. You may apply as. The thickness of the desiccant 23 is, for example, about 100 μm. Moreover, although the ultraviolet curable resin is used for the sealing agent 22, other sealing materials may be used.

  Further, on the insulating substrate 11 on which the organic EL light emitting element 15 is formed on the main surface side in this way, an insulating translucent glass substrate 21 is provided at the peripheral portion so as to cover the organic EL light emitting element 15. Sealing is performed with a sealing agent 22 interposed therebetween, preventing deterioration of operating characteristics due to intrusion of moisture from the surrounding environment, and enabling stable display. An ultraviolet curable resin is used for the sealant 22, but another sealant may be used.

  Further, the insulating substrate 11 is integrally formed with a recess 11 a on the back side opposite to the organic EL element 15. The concave portion 11a formed on the back surface of the insulating substrate 11 is formed, for example, by digging by a sandblast method. The thickness T of the insulating substrate 11 is about 700 μm, and the depth D of the recess 11 a is in the range of about 1/3 to 1/4 of the thickness T, for example, about 200 μm. is there. Further, the concave portion 11a can be formed by means such as molding integrally with the insulating substrate 11.

  Also, for example, an aluminum plate 31 having a high thermal diffusivity is bonded and disposed on the inner bottom surface of the recess 11a formed on the back side of the insulating substrate 11 as a heat radiating member through a silicon adhesive 30 having a high thermal conductivity. ing. The thickness of the aluminum plate 31 is in the range of about 50 μm to about 150 μm. Further, a fine uneven surface 31a is formed on the outermost surface of the aluminum plate 31 that is in contact with the outside air. The fine uneven surface 31a is formed by a sandblasting method or an etching method. The aluminum plate 31 is formed by forming a fine uneven surface on the surface of a standard aluminum plate material by a sandblasting method or an etching method before being bonded to the recess 11a of the insulating substrate 11, and then cutting the aluminum plate 31 to a predetermined size. May be formed.

  In the organic EL display device configured as described above, holes from the hole injection layer 13d to the light emitting layer 13b by applying a predetermined voltage between the cathode 12 and the anode 14 constituting the organic EL light emitting element 15 are provided. And the electrons injected from the electron transport layer 13a cause the light emitting layer 13b to emit light, which is emitted as emitted light L from the translucent glass substrate 21 side toward the upper outside.

  The organic EL display device configured as described above has a configuration in which the concave portion 11a is provided on the back surface side of the insulating substrate 11 and the aluminum plate 31 is simply attached to the concave portion 11a. It can be made thin. In addition, since the organic EL light emitting element 15 and the aluminum plate 31 are disposed close to each other through a thin portion formed at the bottom of the recess 21a, the aluminum plate 31 is closer to the organic EL element 15 that serves as a heat source. Therefore, a large heat dissipation effect can be obtained.

  Furthermore, by providing the fine uneven surface 31a on the outermost surface of the aluminum plate 31, the heat dissipation effect can be further improved. Moreover, when the aluminum plate 31 as a heat radiating member is installed on the insulating substrate 21, since the concave portion 11a is formed on the back side thereof, positioning is much easier than simply attaching the aluminum plate 31, and production is possible. Can be improved.

  In the above embodiment, the aluminum plate 31 having high thermal diffusibility is used as the heat radiating member. However, a copper plate may be used instead of the aluminum plate 31, or an alloy metal plate material thereof may be used. Furthermore, it will not specifically limit if it replaces with these metal plate materials, and is a metal plate material which has thermal diffusivity.

  4 to 19 are plan views of the main part viewed from the back side showing the configuration of another embodiment of the recess 11a formed on the back side of the insulating substrate 11. FIG. As shown in FIGS. 4 to 19, the concave portion 11a formed on the back side of the insulating substrate 11 can be manufactured in various shapes corresponding to the location of the organic EL light emitting element 15 shown in FIG. However, as a method of forming these recesses 11a, it can be formed on the insulating substrate formed in a flat plate shape before the production of the organic EL light emitting element 15, for example, by both the sandblasting method or the etching method. After the production of the organic EL light-emitting element 15, in consideration of damage to the organic EL light-emitting element 15, means for forming the recess 11 a by the sand blast method is preferable to the etching method.

  FIG. 20 is a cross-sectional view schematically illustrating a main part of the organic EL display device according to the second embodiment of the present invention. The same parts as those in FIG. . 20 differs from FIG. 2 in that a metal material having high thermal conductivity, for example, a metal material such as aluminum or copper, is formed in the recess 11a formed on the back side of the insulating substrate 11 over the entire inner wall surface. A metal film 40 is formed by vacuum deposition or sputtering. The metal film 40 has a thickness in the range of about 10 μm to about 250 μm. Further, a fine uneven surface 40 a is formed on the outer surface of the metal film 40. The fine uneven surface 40a is formed by means such as a sand blast method, an etching method, or a rubbing method.

  By providing the metal film 40 in this way, the organic EL light-emitting element 15 and the metal film 40 are disposed close to each other via a thin portion formed at the bottom of the recess 11a, so that the metal film 40 becomes a heat source. Since the position is closer to the organic EL light emitting element 15, the heat generated from the organic EL light emitting element 15 can be effectively diffused to the outside, so that a large heat dissipation effect can be obtained. Furthermore, since the fine uneven surface 40a is provided on the outer surface of the metal film 40, the thermal diffusibility can be further improved. On the other hand, when the back surface of the insulating substrate 11 is roughened by a sandblast method or the like, irregularities are also generated on the inner surface of the metal film 40 formed on the back surface (the surface facing the insulating substrate 11). Thereby, the bonding area between the insulating substrate 11 and the metal film 40 is increased, and the heat generated in the organic EL light emitting element 15 is efficiently discharged to the metal film 40. Since the metal film 40 can be formed after the organic EL light emitting element 15 is fabricated, a countermeasure against heat generation can be easily realized.

  Note that a ground line may be connected to the metal film 40 by welding or the like and electrically connected to a switching element for selecting a pixel and a control element for controlling light emission luminance, although not shown.

  FIG. 21 is a circuit diagram illustrating a configuration example of a pixel of a top emission type organic EL display device to which the present invention is applied. This pixel PX becomes a sub-pixel (sub-pixel) in color display. The pixel PX accumulates display data supplied from the data line DL as an electric charge when the switching thin film transistor TFT1 connected to the scanning line GL and the data line DL and the switching thin film transistor TFT1 selected by the scanning line GL are turned on. A storage capacitor CPR for driving, a thin film transistor TFT2 for driving the organic EL light emitting element 15, and a current supply line CSL.

  The gate electrode of the thin film transistor TFT1 is connected to the scanning line GL, and the drain electrode is connected to the data line DL. The gate electrode of the thin film transistor TFT2 is connected to the source electrode of the thin film transistor TFT1, and one electrode (+ electrode) of the storage capacitor CPR is connected to this connection point. The drain electrode of the thin film transistor TFT2 is connected to the current supply line CSL, and the source electrode is connected to the anode 14 of the organic EL light emitting element 15.

  When the pixel PX is selected by the scanning line GL and the thin film transistor TFT1 is turned on, the display data supplied from the data line DL is stored in the storage capacitor CPR. When the thin film transistor TFT1 is turned off, the thin film transistor TFT2 is turned on and flows from the current supply line CSL to the organic EL display element 15, and this current is maintained for a period of approximately one frame (or one field period). The current flowing at this time is defined by the charge corresponding to the data signal stored in the storage capacitor CPR. This circuit has the simplest configuration, and various other circuit configurations are known.

  FIG. 22 is a plan view of the vicinity of a pixel for explaining a configuration example in which the circuit of the pixel shown in FIG. 21 is realized on a substrate. In the drawing, the same reference numerals as those in FIG. 21 correspond to the same portions, and DE is an opening of a pixel. The thin film transistors TFT1 and TFT2 are arranged in a non-display portion adjacent to the pixel opening DE.

  FIG. 23 is an equivalent circuit including a drive circuit of the organic EL display device. The pixels PX are arranged in a matrix to form a display area AR. The data line DL is driven by the data line driving circuit DDR. The scanning line GL is driven by the scanning line driving circuit GDR. The current supply line CSL is connected to a current supply circuit (not shown) via a current supply bus line CSLB. TM denotes an external input terminal.

  In the above-described embodiments, the top emission type organic EL display device has been described. However, also in the bottom emission type organic EL display device, a recess is provided in the sealing glass substrate, and a heat dissipation member is provided in the recess. Of course, the same effect as described above can be obtained even if it is provided.

  In each of the embodiments described above, the organic EL panel using the organic EL display device has been described. However, the present invention is not limited to this, and a small information terminal (portable, PDA, etc.) that places importance on portability. Needless to say, the present invention can be applied to the organic EL panel for monitoring) or the organic EL display for monitoring.

It is sectional drawing which shows typically the layer structure of the organic electroluminescent light emitting element of the organic electroluminescent display apparatus by this invention. It is principal part sectional drawing which shows typically the structure of Example 1 of the organic electroluminescent display apparatus by this invention. It is the principal part perspective view seen from the back side of the organic electroluminescence display shown in FIG. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is a principal part top view which shows the other Example of the recessed part formed in the back surface side of the sealing glass substrate of the organic electroluminescence display by this invention. It is principal part sectional drawing which shows typically the structure by Example 2 of the organic electroluminescent display apparatus by this invention. It is a circuit diagram which shows the structure of one organic EL light emitting element, ie, 1 pixel vicinity, of the top emission type organic EL display device to which this invention is applied. FIG. 22 is a plan view of the vicinity of a pixel for explaining a configuration example in which the pixel shown in FIG. 21 is realized on a substrate. It is a figure which shows the equivalent circuit including the drive circuit of an organic electroluminescence display.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Insulating substrate, 11a ... Recessed part, 12 ... Cathode, 12a ... Aluminum layer, 12b ... Lithium fluoride layer, 13 ... Organic light emitting film, 13a ... Electron transport Layer, 13b ... light emitting layer, 13c ... hole transport layer, 13d ... hole injection layer, 14 ... anode, 15 ... organic EL light emitting element, 16 ... gas barrier film, DESCRIPTION OF SYMBOLS 21 ... Translucent glass substrate, 22 ... Sealant, 23 ... Desiccant, 30 ... Silicone adhesive, 31 ... Aluminum plate, 31a ... Uneven surface, 40 ... -Metal film, 41a ... Uneven surface.

Claims (7)

  A plurality of organic EL light emitting elements are disposed in a main surface of an insulating substrate that is hermetically sealed with a sealing member interposed at a peripheral portion so as to face the translucent substrate, and the plurality of organic EL light emitting elements An organic EL display device in which a recess is formed on the back surface facing the surface, and a heat dissipation member is disposed in the recess.   The organic EL display device according to claim 1, wherein the heat dissipation member is an aluminum plate.   The organic EL display device according to claim 1, wherein the heat radiating member is a copper plate material.   The organic EL display device according to any one of claims 1 to 3, wherein the heat radiating member is bonded and disposed through a silicon adhesive having high thermal conductivity.   The organic EL display device according to any one of claims 1 to 4, further comprising a fine uneven surface on an outer surface of the heat radiating member.   The organic EL display device according to claim 1, wherein the heat radiating member is a metal film.   The organic EL display device according to claim 6, wherein the metal film has a fine uneven surface on an outer surface.

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