JP2005038763A - Organic el panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL panel in which deterioration of recombination amount of holes and electrons in a luminous layer is suppressed and a long life emitting for a long period of time with a prescribed luminance is realized. <P>SOLUTION: The organic EL panel 1 has an organic EL element 8 made by interposing an organic layer 5 between a positive electrode (transparent electrode) 3 and a negative electrode (backplate) 5 on a translucent support substrate 2. The organic layer 5 comprises at least an electron transporting first luminous layer 5c located on the positive electrode 3 side, and a hole transporting second luminous layer 5d located on the negative electrode 5 side. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic EL panel in which an organic EL (electroluminescence) element in which an organic layer having at least a light emitting layer is sandwiched between a pair of electrodes is disposed on a translucent support substrate.

  As an organic EL panel using an organic EL element, a transparent electrode (first electrode) made of ITO (Indium Tin Oxide) or the like serving as an anode and at least a light emitting layer on a translucent support substrate made of a glass material. It is known that the organic EL element is formed by sequentially laminating an organic layer having a non-translucent back electrode (second electrode) made of aluminum (Al) or the like serving as a cathode. (For example, see Patent Document 1)

Such an organic EL panel emits light by injecting holes from the transparent electrode and injecting electrons from the back electrode, and the holes and electrons recombine in the light emitting layer. There is a demand for extending the life of light emitting for a long time with brightness.
JP 59-194393 A

  However, the organic EL panel has a moving speed or a moving efficiency of holes injected from the transparent electrode and electrons injected from the back electrode due to deterioration of the organic material of the organic layer as the light emission time elapses. As a result, the amount of recombination of holes and electrons in the light emitting layer is decreased, and the light emission luminance is decreased. Therefore, the organic EL panel has a problem in that it is difficult to extend the lifetime because the luminance of the light emitted by the supply balance of electrons and holes to the light emitting layer is lost due to the aging of the organic layer. There was a point.

  In view of such problems, the present invention provides an organic EL panel capable of suppressing the decrease in the amount of recombination of holes and electrons in a light emitting layer and extending the life of light for a long time with a predetermined luminance. With the goal.

In order to solve the above-mentioned problems, the present invention provides an organic EL panel in which an organic EL element in which an organic layer is sandwiched between an anode and a cathode is formed on a translucent support substrate,
The organic layer has at least an electron-transporting first light-emitting layer located on the anode side and a hole-transporting second light-emitting layer located on the cathode side.

  The first light-emitting layer is formed by adding a fluorescent material to an electron-transporting first host material, and the second light-emitting layer is formed on the hole-transporting second host material. It is characterized by adding a fluorescent material.

  Further, the first light emitting layer and the second light emitting layer emit light in substantially the same color.

  The present invention relates to an organic EL panel in which an organic EL element in which an organic layer having at least a light emitting layer is sandwiched between a pair of electrodes is disposed on a translucent support substrate. The reduction in the amount of recombination can be suppressed, and the lifetime can be increased by emitting light for a long time at a predetermined luminance.

  Hereinafter, an embodiment in which the present invention is applied to a segment type organic EL panel will be described with reference to the accompanying drawings.

  In FIG. 1, the organic EL panel 1 includes a support substrate 2, a transparent electrode (anode) 3, an insulating layer 4, an organic layer 5, a back electrode (cathode) 6, and a sealing member 7. Yes.

  The support substrate 2 is a translucent glass substrate having a rectangular shape.

  The transparent electrode 3 is formed by forming a conductive material such as ITO on the support substrate 2 in a layer shape having a film thickness of 50 to 200 nm by means such as a vapor deposition method or a sputtering method. The display segment portion 3a is shaped like a character, the lead portion 3b is formed by pulling out from each segment, and the electrode portion 3c is provided at the end portion of the lead portion 3b. ing. The electrode portion 3c is concentrated on one side of the support substrate 2.

  The insulating layer 4 is made of, for example, a polyimide-based insulating material, and is formed by means such as a photolithography method. The insulating layer 4 has a window portion 4a corresponding to the display segment 3a and a notch portion 4b corresponding to an electrode portion to be described later of the back electrode 6, and in order to clearly display the outline of the light emitting region, the transparent electrode 3 A window portion 4a is formed so as to slightly overlap the peripheral edge portion of the display segment 3a, and is disposed so as to cover the lead portion 3b in order to ensure insulation between the transparent electrode 3 and the back electrode 6.

  As shown in FIG. 2A, the organic layer 5 includes a hole injection layer 5a, a hole transport layer 5b, a first light-emitting layer 5c, a second light-emitting layer 5d, and an electron transport layer 5e formed by a vapor deposition method or the like. The layers are sequentially formed by means to form a layer having a thickness of 80 to 280 nm. The organic layer 5 is disposed with a predetermined size so as to correspond to the location of the window 4a in the insulating layer 4.

  The hole injection layer 5a has a function of taking holes from the transparent electrode 3, and is formed, for example, by laminating an amine compound or the like into a layer having a thickness of 20 to 120 nm by means such as vapor deposition.

  The hole transport layer 5b has a function of transmitting holes to the first light-emitting layer 5c, and is formed by, for example, forming an amine compound or the like into a layer having a film thickness of 20 to 40 nm by means such as vapor deposition.

  As shown in FIG. 2B, the first light-emitting layer 5c is doped into the first host material 5f having an electron transport property by means of a co-evaporation method or the like to form a layer having a thickness of 20 to 60 nm. Formed. The first host material 5f can inject holes and electrons, has a function of emitting light by being transported and recombined with holes and electrons, and has a high electron mobility and a high hole mobility. It has low characteristics and is made of, for example, a diphenylanthracene derivative that is an anthracene derivative. The fluorescent material 5g has a function of emitting light in response to recombination of electrons and holes, exhibits blue-green light emission, and is made of, for example, a styrylamine compound. The doping amount of the fluorescent material 5g is desirably configured so as not to cause concentration quenching of the first light emitting layer 5c.

  As shown in FIG. 2B, the second light-emitting layer 5d is a layered film having a film thickness of 20 to 60 nm by doping the second host material 5h having a hole transport property with a fluorescent material 5g by means of a co-evaporation method or the like. Formed. The second host material 5h can inject holes and electrons, has a function of emitting light by being transported and recombined with holes and electrons, and has a high hole mobility and high electron mobility. It has low characteristics, and is made of, for example, a distyrylarylene derivative.

  The electron transport layer 5e has a function of transmitting electrons to the light-emitting layer 5c, and is formed by forming, for example, aluminum quinolinol (Alq3), which is a chelate compound, in a layer shape having a film thickness of 20 to 60 nm by means such as vapor deposition. .

  The back electrode 6 is formed in a layer shape having a film thickness of 50 to 200 nm by means of vapor deposition or the like using a metal conductive material such as aluminum (Al), aluminum lithium (Al: Li), magnesium silver (Mg: Ag), or the like. The lead part 6a provided on one side of the support substrate 2 is electrically connected. Note that an electrode portion (leading portion) 6b is provided at the terminal portion of the lead portion 6a, and the lead portion 6a and the electrode portion 6b are formed of the same material as the transparent electrode 3.

  As described above, the transparent electrode 3, the insulating layer 4, the organic layer 5, and the back electrode 6 are sequentially laminated on the support substrate 2 to obtain the organic EL element 8. The organic EL element 8 obtains blue-green light emission by recombining holes from the transparent electrode 3 and electrons from the back electrode in the first light emitting layer 5c and the second light emitting layer 5d. . In an organic EL device having a conventional single-layer light emitting layer, light is emitted mainly by recombination of holes and electrons in a region near the interface between the light emitting layer and the hole transport layer. In the organic EL element 8 of the form, the first light-emitting layer 5c having an electron transport property is formed on the transparent electrode 3 side for injecting holes, and the hole transport property is provided on the back electrode 6 side for injecting electrons. Since the second light emitting layer 5d is formed, a part of the holes from the hole transport layer 5b is captured in a region near the hole transport layer 5b of the first light emitting layer 5c, and the electron transport layer 5e A part of the electrons of the second light-emitting layer 5d is captured in the region near the electron transport layer 5e, and the region near the hole transport layer 5b of the first light-emitting layer 5c and the electron transport layer of the second light-emitting layer 5d. Recombination of holes and electrons in the vicinity of 5e and in the vicinity of the interface between the first light emitting layer 5c and the second light emitting layer 5d Is carried out, and the first light-emitting layer 5c and the second emission layer 5d emits light, and has a light-emitting region in the light emitting layer can be wider than the conventional. At this time, the efficiency of recombination of holes and electrons is affected by the amount of electrons transported from the second light emitting layer 5d because the first light emitting layer 5c has many holes and few electrons. In addition, since the second light emitting layer 5d has few holes and many electrons, it is influenced by the amount of holes transported from the first light emitting layer 5c. Therefore, even if the amount of holes and electrons supplied to the first and second light-emitting layers 5c and 5d changes due to deterioration of the organic material of the organic layer 5 with the passage of light emission time, etc. The amount of holes transported to the first light emitting layer 5c is determined by the electron transport characteristics of the second light emitting layer 5d, and the amount of electrons transported to the second light emitting layer 5d is the first light emission. Since it is determined by the hole transport characteristics of the layer 5c, it is not easily affected by changes in the supply amount of holes and electrons, and the light emission luminance in the first light-emitting layer 5c and the second light-emitting layer 5d over time Can be suppressed. 3 shows a case where the same constant current is applied to an organic EL panel including an organic EL element having a conventional single-layer light emitting layer having the same light emitting area and an organic EL panel 1 including the organic EL element 8 of the present embodiment. The change of the light emission luminance with the passage of the light emission time is shown, the characteristic S1 shows the characteristic of the conventional organic EL panel, and the characteristic S2 shows the characteristic of the organic EL panel 1 of the present embodiment. The organic EL panel 1 has the same initial luminance as that of a conventional organic EL panel, and a decrease in light emission luminance with the passage of light emission time is suppressed as compared with the conventional organic EL panel. It is clear from FIG. 3 that the EL panel 1 is superior to the conventional organic EL panel.

  The sealing member 7 is formed by forming a concave portion 7a in a flat plate member made of, for example, a glass material by an appropriate method such as sandblasting, cutting, and etching. The sealing member 7 is airtightly disposed on the support substrate 2 with a support portion 7b formed so as to surround the recess 7a on an adhesive made of, for example, an ultraviolet curable epoxy resin. The organic EL element 8 is sealed with the support substrate 2. The sealing member 7 is configured to be slightly smaller than the support substrate 2 so that the electrode portion 3c of the transparent electrode 3 and the electrode portion 6b of the back electrode 6 are exposed to the outside.

  In the organic EL panel 1, the organic layer 5 sandwiched between the transparent electrode 3 and the back electrode 6 has an electron transporting first light emitting layer 5c positioned on the transparent electrode 3 side and a positive electrode positioned on the back electrode 5 side. And a hole-transporting second light-emitting layer 5d. The first light-emitting layer 5c is formed by doping the first host material 5f with electron transport with a fluorescent material 5g, and the second light-emitting layer 5d is a second host with hole transport. The material 5h is doped with a fluorescent material 5g. Further, the first light emitting layer 5c and the second light emitting layer 5d emit light in substantially the same color. Is possible. From the above configuration, the organic EL panel 1 has a wider light emitting region than the conventional organic EL panel having a single light emitting layer, and the efficiency of recombination of holes and electrons in the first light emitting layer 5c. Is determined by the electron transport property of the second light emitting layer 5d, and in the second light emitting layer 5d, it is determined by the hole transport property of the first light emitting layer 5c. Even if the amount of holes and electrons supplied to the first and second light-emitting layers 5c and 5d changes due to deterioration of the organic material, etc., holes due to changes in the amount of holes and electrons supplied It is less affected by the recombination efficiency between electrons and electrons and emits light for a long time with a predetermined luminance while suppressing a decrease in the amount of recombination of holes and electrons in the first and second light emitting layers 5c and 5d. Long life is possible.

  Although the present embodiment is a segment type organic EL panel 1, the present invention is also applicable to a dot matrix type organic EL panel.

  Moreover, although the organic EL panel 1 of this embodiment was the structure which has the 1st light emitting layer 5c located in the transparent electrode 3 side as a light emitting layer, and the 2nd light emitting layer 5d located in the back electrode side. In the present invention, the light emitting layer may be formed by laminating three or more light emitting layers.

  In the organic EL panel 1 of the present embodiment, the first and second light emitting layers 5c and 5d are formed by doping the first host material 5f and the second host material 5h with the common fluorescent material 5g. However, in the present invention, the first and second host materials may be doped with different fluorescent materials.

Sectional drawing which shows the organic electroluminescent panel to which this invention was applied. The expanded sectional view which shows an organic EL element same as the above. The figure which shows the relationship between the light emission time of the organic electroluminescent panel same as the above, and the conventional organic electroluminescent panel, and light emission luminance.

Explanation of symbols

1 Organic EL Panel 2 Support Substrate 3 Transparent Electrode (Anode)
4 Insulating Layer 5 Organic Layer 5a Hole Injection Layer 5b Hole Transport Layer 5c First Light-Emitting Layer 5d Second Light-Emitting Layer 5e Electron Transport Layer 5f First Host Material 5g Second Host Material 5h Fluorescent Material 6 Back Electrode (cathode)
7 Sealing member 8 Organic EL element

Claims (3)

An organic EL panel formed by forming an organic EL element having an organic layer sandwiched between an anode and a cathode on a translucent support substrate,
The organic layer includes at least an electron-transporting first light-emitting layer located on the anode side and a hole-transporting second light-emitting layer located on the cathode side panel. The first light emitting layer is formed by adding a fluorescent material to an electron transporting first host material, and the second light emitting layer is formed by adding a fluorescent material to a hole transporting second host material. The organic EL panel according to claim 1, wherein The organic EL panel according to claim 1, wherein the first light emitting layer and the second light emitting layer emit light in substantially the same color.

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