JP2011096615A - Manufacturing method of organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To strictly control concentration of dopant in a host material at the time of layer-forming of an organic EL element. <P>SOLUTION: In the manufacturing method of an organic electroluminescent element 7, a positive electrode 4, a both charge transporting region 103, a light emitting region 101, a both charge transporting region 103 and a negative electrode 9 are formed in this order on an insulative substrate 1. At this time, the positive electrode 4 is composed of an acceptor and the negative electrode 9 is composed of a donor. Then, the substrate is heated for an annealing treatment and the acceptor composing the positive electrode 4 is heat-diffused in the both charge transporting region 103 neighboring the positive electrode 4 and the donor composing the negative electrode 9 is heat-diffused into the both charge transporting region 103 neighboring the negative electrode 9. As a result, a hole transporting region 100 and an electron transporting region 102 where concentration of dopant is made continuously gradient are formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an organic electroluminescent device that achieves high brightness, high efficiency, and long life with a simple structure.

  In recent years, there has been a growing need for display devices using thin flat panel displays (FPDs) from display devices using cathode ray tubes, which have been the mainstream in the past. There are various types of FPD, for example, non-self-luminous liquid crystal display (LCD), self-luminous plasma display panel (PDP), inorganic electroluminescence (inorganic EL) display, or organic electroluminescence (organic EL). A display or the like is known.

  In particular, organic EL displays are actively researched and developed because the elements used for display (organic EL elements) are thin and lightweight, and have characteristics such as low voltage drive, high luminance, and self-luminous emission. Has been done. Recently, application of organic EL elements to light sources such as electrophotographic copying machines or printers or light emission is expected. When an organic EL element is used for light emission, the organic EL element has surface emission, has high color rendering properties, and has an advantage that light control is easy. Furthermore, fluorescent lamps contain mercury, but organic EL elements do not contain mercury, and there are many advantages such as that the organic EL elements do not contain ultraviolet rays.

  The organic EL element has a pair of electrodes (anode and cathode) on a substrate, and has at least a light emitting layer formed by doping a host material with an organic light emitting material between the pair of electrodes. . In general, a hole transport layer or a hole injection layer or the like is provided between the light emitting layer and the anode, and an electron injection layer or an electron transport layer or the like is provided between the light emitting layer and the cathode. There is also a method of doping each layer with a dopant such as an acceptor or a donor in order to increase carrier injection efficiency from the electrode to the organic layer and carrier transport efficiency to the light emitting layer. Each layer (light emitting layer, hole injection layer, electron injection layer, etc.) constituting the organic EL element is formed using different host materials, and the organic EL element having a multilayer structure is a heterojunction type. is there. On the other hand, an organic EL element in which each layer is formed as a single layer by doping a single host material with a dopant such as an organic light emitting material, an acceptor, or a donor is a homojunction type.

  As a method for doping a host material with a dopant such as an organic light emitting material, an acceptor, or a donor, a co-evaporation method is generally used. A desired layer can be formed by co-evaporating a host material and a dopant such as an organic light-emitting material, a donor, or an acceptor. Specifically, the host material and the dopant are used as separate vapor deposition sources, and vapor deposition is performed by controlling the respective vapor deposition rates. In such a co-evaporation method, it is necessary to accurately control the deposition rate of the host material and the dopant at the time of deposition, so that it is difficult to control the concentration in the film thickness direction. As a result, the dopant concentration is sparse, carrier injection / transport properties are hindered, and the characteristics of the organic EL element are degraded.

  In order to solve the above problem, Patent Documents 1 to 3 disclose a method of uniformly diffusing a dopant into a host material during layer formation. In the method of manufacturing an organic EL element disclosed in Patent Document 1, a host material is vapor-deposited, and a dopant is vapor-deposited on the vapor-deposited host material. Then, the dopant is diffused in the host material by exposing the organic EL element to fluid vapor or fluid mixture vapor. Thereby, the dopant can be uniformly dispersed in the host material.

  Patent Document 2 discloses a method in which a dopant is dispersed in a host material by controlling the temperature of the substrate to 40 to 200 ° C. when the host material and the dopant are deposited on the substrate by vacuum deposition. It is disclosed. According to this, the dopant is thermally diffused, the concentration of the dopant in the film thickness direction can be controlled, and the dopant can be diffused uniformly.

  On the other hand, Patent Document 3 discloses a method of depositing a dopant on a host material, irradiating the dopant with a laser beam a plurality of times, and injecting or diffusing the dopant into the host material. According to this, the diffusibility of the dopant in the thickness direction of the host material (in the thickness direction of the organic EL element) can be enhanced by locally abruptly heating the irradiated portion by laser light irradiation. Further, by cooling the irradiated portion of the host material when the laser beam is not irradiated, it is possible to suppress the diffusion of the dopant in the surface direction of the host material (the surface direction of the organic EL element).

JP 2000-150151 A (published on May 30, 2000) Japanese Patent Laid-Open No. 7-320872 (released on December 8, 1995) JP 2005-158357 A (released on June 16, 2005)

  However, in the manufacturing methods disclosed in Patent Documents 1 to 3 described above, it is difficult to strictly control the dopant concentration.

  In particular, the manufacturing method disclosed in Patent Document 2 heats the substrate of the organic EL element in a vacuum, but it is difficult to strictly control the temperature of the substrate in a vacuum. In particular, in the manufacturing method disclosed in this document, a heater is installed on the back side of the substrate to heat, but such a heating method causes uneven temperature distribution in the thickness direction of the substrate. Therefore, it is difficult to strictly control the dopant concentration distribution. As a result, the carrier injecting property / transporting property of the organic EL element deteriorates, and the characteristics of the organic EL element deteriorate.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a manufacturing method capable of strictly controlling the concentration of dopant in a host material when forming a layer of an organic EL element. It is in.

  In order to solve the above problems, a method for manufacturing an organic electroluminescent element according to the present invention is formed between a first electrode and a second electrode, and the first electrode and the second electrode, and the organic light emitting material is doped. A method for producing an organic electroluminescent device comprising an organic layer having at least a light emitting region formed on a substrate, wherein transport of a first carrier injected from the first electrode into the organic layer is performed on the substrate. A first electrode forming step for forming the first electrode made of the first dopant to be promoted; a first host region forming step for forming a first host region made of a predetermined host material on the first electrode; and A light emitting region forming step of forming the light emitting region in which the organic light emitting material is doped in a predetermined host material on the first host region, and a predetermined host material on the light emitting region After the second host region forming step for forming the second host region, the second electrode forming step for forming the second electrode on the second host region, and the first host region forming step, And a first carrier transport region forming step of forming a first carrier transport region for transporting the first carrier in the first host region by heating the substrate.

  According to said method, in the manufacturing method of the organic electroluminescent (organic EL) element concerning this invention, a 1st electrode, a 1st host area | region, a light emission area | region, a 2nd host area | region, and a 2nd electrode are provided on a board | substrate. Form in order. At this time, the first electrode is formed of a first dopant that promotes transport of the first carrier injected from the first electrode. Thereafter, the substrate is heated and annealed to thermally diffuse the first dopant constituting the first electrode into the first host region adjacent to the first electrode, thereby forming the first carrier transport region.

  Thus, by performing the annealing treatment, the first dopant can be sufficiently diffused in the first host region (first carrier transport region), and the concentration of the first dopant can be prevented from being sparse. it can. Therefore, according to the manufacturing method of the organic EL element which concerns on this invention, the density | concentration control of a 1st dopant can be performed strictly.

  Conventionally, a co-evaporation method is generally used for manufacturing an organic EL element. Specifically, the host material and the dopant are used as separate vapor deposition sources, and vapor deposition is performed by controlling the respective vapor deposition rates. In such a co-evaporation method, it is necessary to accurately control the deposition rate of the host material and the dopant at the time of deposition, so that it is difficult to control the concentration in the film thickness direction. As a result, the dopant concentration is sparse, carrier injection / transport properties are hindered, and the characteristics of the organic EL element are degraded.

  However, in the method of manufacturing an organic EL device according to the present invention, after forming the first host region made of the host material, the first dopant is thermally diffused by annealing to form the first carrier transport region. Yes. Therefore, unlike the conventional case, it is not necessary to accurately control the deposition rate of the host material and the first dopant. Moreover, the manufacturing method of the organic EL element according to the present invention is very simple and does not require a manufacturing apparatus such as a complicated vapor deposition apparatus, so that the manufacturing cost can be reduced.

  Moreover, when manufacturing an organic EL element using a vacuum evaporation method, it is difficult to control the temperature at the time of performing an annealing process under vacuum. However, in the method for manufacturing an organic EL element according to the present invention, since the annealing process can be performed under vacuum, strict temperature control is possible. Therefore, the concentration of the first dopant can be controlled to a desired concentration under strict temperature control.

  Moreover, in the manufacturing method of the organic electroluminescent element which concerns on this invention, Furthermore, in the said 2nd electrode formation process, the said consisting of a dopant which accelerates | stimulates the transport of the 2nd carrier inject | poured into the said organic layer from the said 2nd electrode. A second carrier which forms a second carrier transport region in the second host region for transporting the second carrier by forming the second electrode and heating the substrate after the second electrode forming step. And a transport region forming step.

  According to the above method, the host region to be annealed can be selected at any time in consideration of the carrier injection property / transport property of the electrode. Therefore, the carrier transport region doped with the dopant can be formed at a desired location.

  In the method for manufacturing an organic electroluminescent element according to the present invention, the first electrode and the second electrode, and the light emitting region formed between the first electrode and the second electrode and doped with an organic light emitting material A method for producing an organic electroluminescence device comprising an organic layer having at least an organic layer on the substrate, the first electrode forming step of forming the first electrode on the substrate, and a predetermined on the first electrode A first host region forming step for forming a first host region made of the host material, and a light emitting region forming for forming the light emitting region in which the organic light emitting material is doped in a predetermined host material on the first host region A second host region forming step of forming a second host region made of a predetermined host material on the light emitting region, and the second electrode on the second host region. After the second electrode forming step of forming the second electrode with a dopant that promotes transport of the second carrier injected into the organic layer, and after the second electrode forming step, the substrate is heated to A second carrier transport region forming step of forming a second carrier transport region for transporting the second carrier in the second host region.

  According to said method, in the manufacturing method of the organic electroluminescent (organic EL) element concerning this invention, a 1st electrode, a 1st host area | region, a light emission area | region, a 2nd host area | region, and a 2nd electrode are provided on a board | substrate. It will be formed in order. At this time, the second electrode is formed of a second dopant that promotes transport of the second carrier injected from the second electrode. Thereafter, the substrate is heated and annealed to thermally diffuse the second dopant constituting the second electrode into the second host region adjacent to the second electrode, thereby forming a second carrier transport region.

  Thus, by performing the annealing treatment, the second dopant can be sufficiently diffused in the second host region (second carrier transport region), and the concentration of the second dopant can be prevented from being sparse. it can. Therefore, according to the manufacturing method of the organic EL element which concerns on this invention, the density | concentration control of a 2nd dopant can be performed strictly.

  Conventionally, a co-evaporation method is generally used for manufacturing an organic EL element. Specifically, the host material and the dopant are used as separate vapor deposition sources, and vapor deposition is performed by controlling the respective vapor deposition rates. In such a co-evaporation method, it is necessary to accurately control the deposition rate of the host material and the dopant at the time of deposition, so that it is difficult to control the concentration in the film thickness direction. As a result, the dopant concentration is sparse, carrier injection / transport properties are hindered, and the characteristics of the organic EL element are degraded.

  However, in the method for manufacturing an organic EL element according to the present invention, after the second electrode is formed, the second dopant is thermally diffused by performing an annealing process to form the second carrier transport region. Therefore, it is not necessary to accurately control the deposition rate of the host material and the second dopant as in the prior art. Moreover, the manufacturing method of the organic EL element according to the present invention is very simple and does not require a manufacturing apparatus such as a complicated vapor deposition apparatus, so that the manufacturing cost can be reduced.

  Moreover, when manufacturing an organic EL element using a vacuum evaporation method, it is difficult to control the temperature at the time of performing an annealing process under vacuum. However, in the method for manufacturing an organic EL element according to the present invention, since the annealing process can be performed under vacuum, strict temperature control is possible. Therefore, the concentration of the second dopant can be controlled to a desired concentration under strict temperature control.

  In the method for manufacturing an organic electroluminescence element according to the present invention, the first carrier transport region forming step and the second carrier transport region forming step are simultaneously performed.

  According to said method, since a 1st carrier transport area | region and a 2nd carrier transport area | region can be formed at once, a manufacturing process can be simplified more.

  In the method for manufacturing an organic electroluminescence element according to the present invention, the first carrier transport region forming step is performed after the second electrode forming step, and the first electrode and the first carrier are formed in the first carrier transport region forming step. It is characterized by applying a voltage to two electrodes.

  Moreover, in the manufacturing method of the organic electroluminescent element which concerns on this invention, a voltage is applied to said 1st electrode and 2nd electrode in said 2nd carrier transport area | region formation process, It is characterized by the above-mentioned.

  According to the above method, by performing the annealing process in a state where a voltage is applied, the diffusion rate of the dopant can be improved and the time required for heating the substrate can be shortened.

  Moreover, in the manufacturing method of the organic electroluminescent element which concerns on this invention, the said board | substrate is heated at the temperature which does not exceed the glass transition temperature of the said board | substrate in the said 1st carrier transport area | region formation process.

  Moreover, in the manufacturing method of the organic electroluminescent element which concerns on this invention, the said board | substrate is heated at the temperature which does not exceed the glass transition temperature of the said board | substrate in the said 2nd carrier transport area | region formation process.

  According to the above method, the dopant can be sufficiently thermally diffused in the host region. Further, the substrate constituting the organic EL element can be prevented from melting.

  Moreover, in the manufacturing method of the organic electroluminescent element which concerns on this invention, a transparent electrode is formed on the said board | substrate in the said 1st electrode formation process, The said 1st electrode is formed on the said transparent electrode, It is characterized by the above-mentioned. Yes.

  Moreover, in the manufacturing method of the organic electroluminescent element which concerns on this invention, a transparent electrode is formed on the said board | substrate in the said 2nd electrode formation process, The said 2nd electrode is formed on the said transparent electrode, It is characterized by the above-mentioned. Yes.

  According to said method, by having a transparent electrode other than an electrode, the transmittance | permeability of the light through the said electrode side improves more. Therefore, the light emitted from the organic EL element can be extracted more efficiently.

  Further, in the method for manufacturing an organic electroluminescence element according to the present invention, in the first host region forming step, the first host region made of both charge transport materials is formed, and in the light emitting region forming step, the first host region is formed. In the second host region forming step, the first host is formed by doping the organic light emitting material with the same charge transporting material as the both charge transporting materials constituting one host region. The first host region is formed of the same charge transporting material as the both charge transporting materials constituting the region.

  According to the above method, the first host region, the light emission amount region, and the second host region can be formed as the same layer, not as separate layers. Therefore, since the layer configuration in the organic EL element is simplified, the manufacturing cost of the organic EL element can be further reduced.

  In the method for producing an organic EL element according to the present invention, the concentration of the dopant in the layer of the organic EL element can be strictly controlled and can be produced by a simple method.

It is a figure which shows the density | concentration of each material which comprises the cross section of the organic electroluminescent element which concerns on one Embodiment of this invention, and the said element. It is a figure which shows the cross section of the organic electroluminescent display apparatus which concerns on one Embodiment of this invention. (A) is a figure which shows the cross section of the organic electroluminescent element before performing an annealing process, (b) is a figure which shows the cross section of the organic electroluminescent element after performing an annealing process. It is a figure which shows the cross section of the organic electroluminescent display apparatus which concerns on one Embodiment of this invention. It is a figure which shows the density | concentration of each material which comprises the cross section of the organic electroluminescent element which concerns on one Embodiment of this invention, and an organic electroluminescent element. It is a figure which shows the cross section of the organic electroluminescent display apparatus which concerns on one Embodiment of this invention. It is a figure which shows the density | concentration of each material which comprises the cross section of the organic electroluminescent element which concerns on one Embodiment of this invention, and an organic electroluminescent element. (A) is a figure which shows the cross section of the organic electroluminescent element before performing an annealing process, (b) is a figure which shows the cross section of the organic electroluminescent element after performing an annealing process.

[First embodiment]
(Outline of organic electroluminescence display device 10)
An outline of the organic EL display device 10 according to the present embodiment will be described with reference to FIG. FIG. 2 is a view showing a cross section of the organic electroluminescence display device 10 (hereinafter referred to as the organic EL display device 10). As shown in this figure, an organic EL display device 10 includes an insulating substrate (substrate) 1, a thin film transistor (TFT) 2, an interlayer insulating film 3, an anode (first electrode) 4, an edge cover 5, an organic EL layer (organic) Layer) 8 and a cathode (second electrode) 9.

  A plurality of TFTs 2 are formed on the insulating substrate 1 at a predetermined interval. A flattened interlayer insulating film 3 is disposed on the TFT 2. Contact holes are formed in the interlayer insulating film 3. The terminal of the TFT 2 is electrically connected to the anode 4 through the contact hole. An organic EL layer 8 and a cathode 9 are formed on the anode 4 at a position facing the TFT 2. The insulating substrate 1, the anode 4, the organic EL layer 8, and the cathode 9 constitute an organic EL element (organic electroluminescence element) 7. An edge cover 5 is provided between the organic EL elements 7.

  As will be described in detail later, the anode 4, the organic EL layer 8, and the cathode 9 according to the present embodiment constitute a single layer containing both charge transport materials (host materials). The organic EL layer 8 is formed between a pair of electrodes (anode 4 and cathode 9). In this embodiment, one of the pair of electrodes is an anode, and the other electrode is a cathode. .

  The anode 4 is formed of an acceptor (first dopant) having a concentration of 100 wt% with respect to both charge transport materials, and the charge transport material is doped so that the concentration of the acceptor decreases toward the cathode 9. Has been. Further, the cathode 9 is formed of a donor (second dopant) having a concentration of 100% with respect to both charge transporting materials, and the both charge transporting materials are arranged so that the concentration of the donors decreases toward the anode 4. Is doped. In both charge transporting materials, there is a gap between the region where the acceptor concentration is continuously decreased and the region where the donor concentration is continuously decreased so that the acceptor concentration is continuously decreased. There is a region doped with an organic light emitting material.

  According to said structure, the injection | pouring of the hole (1st carrier) from the anode 4 and the injection | pouring of the electron (2nd carrier) from the cathode 9 can be performed efficiently. Furthermore, the propagation of holes and electrons in the organic EL layer 8 can also be performed efficiently. This will be described in detail later.

(Outline of insulating substrate 1)
As described above, the insulating substrate 1, the thin film transistor (TFT) 2, the interlayer insulating film 3, the anode 4, the edge cover 5, the organic EL layer 8, and the cathode 9 are provided. Each member will be described in detail below.

  First, the insulating substrate 1 will be described. As the insulating substrate 1, for example, an inorganic material substrate made of glass, quartz, or the like, or a plastic substrate made of polyethylene terephthalate, polyimide resin, or the like can be used. In addition, a substrate in which a metal substrate made of aluminum (Al) or iron or the like is coated with an insulator made of silicon oxide or an organic insulating material can be used. Alternatively, a substrate obtained by insulating the surface of a metal substrate made of Al or the like by a method such as anodization can be used.

  Which type of insulating substrate 1 is actually used considers the type of TFT 2. For example, when the TFT 2 made of polycrystalline silicon is used, since the TFT 2 is formed by a low temperature process, it is preferable to use a substrate that does not melt at a temperature of 500 ° C. or less and does not cause distortion. On the other hand, when the TFT 2 made of polycrystalline silicon is used, since the TFT 2 is formed by a high-temperature process, it is preferable to use a substrate that does not melt at a temperature of 1000 ° C. or less and does not cause distortion.

  In addition, when taking out the light emitted from the organic EL layer 8 from the insulating substrate 1 side, it is necessary to use a transparent or translucent substrate.

(Outline of TFT2)
The TFT 2 will be described. The TFT 2 has a function as a switching element of each organic EL element 7. Therefore, examples of the material constituting the TFT 2 include inorganic semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, and cadmium selenide, polythiophene derivatives, and organic semiconductor materials such as pentacene. Instead of TFT2, a metal-insulator-metal (MIM) diode can also be used.

(Outline of interlayer insulating film 3)
The interlayer insulating film 3 will be described. For the interlayer insulating film 3, for example, an inorganic material such as silicon oxide or silicon nitride, an acrylic resin, a polyimide resin, a photosensitive sol-gel material, an organic resin material such as a novolac resin, or the like can be used. Examples of the acrylic resin include Optomer series manufactured by JSR Corporation. Moreover, as said polyimide resin, the photo nice series etc. of Toray Industries, Inc. are mentioned, for example. However, in the case where the structure of the organic EL display device 10 is a bottom emission type, the interlayer insulating film 3 is required to have light transmittance, and thus an opaque material such as polyimide resin is not suitable.

(Configuration of anode 4, organic EL layer 8 and cathode 9)
As described above, the anode 4, the organic EL layer 8, and the cathode 9 according to this embodiment are characterized by being composed of a single layer containing both charge transport materials. The detailed configuration will be described with reference to FIG. FIG. 1 is a view showing a cross section of the organic EL element 7 and the concentration of each material constituting the organic EL element 7.

  As shown in FIG. 1, the organic EL element 7 is formed by forming a single layer having an anode 4, an organic EL layer 8, and a cathode 9 on an insulating substrate 1. In this figure, the TFT 2 and the interlayer insulating film 3 are omitted. The organic EL layer 8 is divided into a hole transport region (first carrier transport region) 100, a light emitting region 101, and an electron transport region (second carrier transport region) 102. The hole transport region 100 is located on the anode 4 side, while the electron transport region 102 is located on the cathode 9 side. The light emitting region 101 is located between the hole transport region 100 and the electron transport region 102.

  In the organic EL element 7, the anode 4 is formed of an acceptor having a concentration of 100 wt% with respect to both charge transporting materials. The acceptor is doped so that the concentration of the acceptor decreases toward the light emitting region 101. That is, the material of the anode 4 is doped in the organic EL layer 8 as an acceptor. Specifically, when the organic EL element 7 is formed, the acceptor constituting the anode 4 is thermally diffused by annealing, so that the acceptor concentration has a continuous gradient in the hole transport region 100. A detailed manufacturing method will be described later. A region where a concentration gradient is given so that the acceptor concentration 21 continuously decreases is the hole transport region 100.

  As shown in FIG. 1, the acceptor concentration 21 in the anode 4 is 100 wt%. In the hole transport region 100, the acceptor concentration 21 continuously decreases from 100 wt% toward the cathode 9 from the anode 4 and reaches 0 wt% when reaching the light emitting region 101. Along with this, the concentration 23 of both charge transporting materials continuously increases from 0 wt% to 100 wt% before reaching the light emitting region 101.

  The light emitting region 101 between the hole transport region 100 and the electron transport region 102 is doped with an organic light emitting material. In this case, the organic light emitting material is preferably doped so that the concentration with respect to both charge transport materials is preferably about 1 wt% to 20 wt%, more preferably about 6 wt%.

  However, the gradient in the light emitting region 101 is such that the concentration of the organic light emitting material continuously increases from the end surface on the hole transport region 100 side and the end surface on the electron transport region 102 side toward the center of the light emitting region 101. More preferably, it is attached. Further, a region that does not include an acceptor and an organic light emitting material may be included between the hole transport region 100 and the light emitting region 101. This can prevent the excitons generated in the organic light emitting material from deactivating due to energy transfer to the acceptor. Similarly, a region not including a donor and an organic light emitting material may be included between the electron transport region 102 and the light emitting region 101. Thereby, it is possible to prevent the excitons generated in the organic light emitting material from deactivating due to energy transfer to the donor.

  On the other hand, in the organic EL element 7, the cathode 9 is formed from a donor having a concentration of 100 wt% with respect to both charge transporting materials. The donor is doped so that the donor concentration 22 decreases continuously from 100 wt% as it goes from the cathode 9 to the light emitting region 101. That is, the material of the cathode 9 is doped in the organic EL layer 8 as a donor. Specifically, when the organic EL element 7 is formed, the donor constituting the cathode 9 is thermally diffused by annealing, so that the donor concentration in the electron transport region 102 has a continuous gradient. A detailed manufacturing method will be described later. A region where a concentration gradient is given so that the donor concentration 22 continuously decreases is an electron transport region 102.

  As shown in FIG. 1, the donor concentration 22 in the cathode 9 is 100 wt%. In the electron transport region 102, the donor concentration 22 continuously decreases from 100 wt% toward the anode 4 from the cathode 9, and becomes 0 wt% when reaching the light emitting region 101. Along with this, the concentration 23 of both charge transporting materials continuously increases from 0 wt% to 100 wt% before reaching the light emitting region 101.

  According to the above configuration, the anode 4 itself is made of the acceptor material, and the acceptor is doped so that its concentration decreases as it goes to the light emitting region 101. Thus, at the boundary portion between the anode 4 and the hole transport region 100, the work function of the anode 4 and the highest occupied level (HOMO) in which holes propagate through the acceptor substantially coincide. Therefore, no energy barrier is generated at the boundary portion between the anode 4 and the hole transport region 100, and holes can be efficiently propagated from the anode 4 to the hole transport region 100. Further, at the boundary between the light emitting region 101 and the hole transport region 100, the concentration of the organic light emitting material in the light emitting region 101 is low, and the concentration of both charge transporting materials in the hole transport region 100 is 100 wt%. . Therefore, the HOMO level of both charge transporting materials in the acceptor-doped region and the HOMO level in which holes propagate through the acceptor substantially coincide, and holes are efficiently transferred from the hole transport region 100 to the light emitting region 101. Can propagate.

  Similarly, according to the above configuration, the cathode 9 itself is made of a donor material, and the donor is doped so that its concentration decreases as it goes toward the light emitting region 101. Thus, at the boundary between the cathode 9 and the electron transport region 102, the work function of the cathode 9 and the lowest vacancy level (LUMO) at which electrons propagate through the donor substantially coincide. Therefore, an energy barrier is not generated at the boundary between the cathode 9 and the electron transport region 102, and electrons can be efficiently propagated from the cathode 9 to the electron transport region 102. Further, at the boundary between the light emitting region 101 and the electron transporting region 102, the concentration of the organic light emitting material in the light emitting region 101 is low, and the concentration of both charge transporting materials in the electron transporting region 102 is 100 wt%. Therefore, the LUMO level of both charge transporting materials in the electron transporting region and the LUMO level at which electrons propagate through the donor substantially coincide with each other, and electrons can be efficiently propagated from the electron transporting region 101 to the light emitting region 102. it can.

  As described above, in the organic EL element 7 according to this embodiment, no energy barrier is generated between both electrodes and the organic EL layer 8, and holes and electrons can be efficiently injected and transported. Therefore, the drive voltage of the organic EL element 7 can be reduced. Furthermore, in the organic EL element 7, the anode 4, the organic EL layer 8, and the cathode 9 are composed of a single layer. Thereby, the layer structure in the organic EL element 7 is simplified, and the manufacturing cost of the organic EL element 7 can be significantly reduced.

  In this embodiment, the acceptor concentration and the donor concentration have a linear gradient, but the present invention is not limited to this as long as it is a continuous gradient. For example, an exponential gradient may be used.

(Outline of anode 4)
Hereinafter, the anode 4 will be described in detail. The anode 4 is formed in an island shape on the insulating substrate 1 (on the interlayer insulating film 3), and is electrically connected to the TFT 2 through a contact hole formed in the interlayer insulating film 3. The anode 4 has a function of injecting holes into the organic EL layer 8. Further, as described above, the anode 4 is formed from an acceptor having a concentration of 100 wt% with respect to both charge transporting materials. Therefore, in the present invention, the acceptor is required to be a conductive material.

Examples of the material (acceptor) constituting the anode 4 include molybdenum oxide (MoO ₂ ), vanadium pentoxide (V ₂ O ₅ ), gold (Au), nickel (Ni), platinum (Pt), and tungsten (W). Or an inorganic material such as iridium (Ir).

(Outline of cathode 9)
Next, the cathode 9 will be described. The cathode 9 is provided so as to cover the organic EL layer 8 and the edge cover 5. The cathode 9 has a function of injecting electrons into the organic EL layer 8. Further, as described above, the cathode 9 is formed from a donor having a concentration of 100 wt% with respect to both charge transporting materials. Therefore, in the present invention, the donor is required to have conductivity.

  Examples of the material (donor) constituting the cathode 9 include alkali metals, alkaline earth metals, rare earth elements, aluminum (Al), silver (Ag), copper (Cu), indium (In), or cesium (Cs). And inorganic materials.

(Outline of organic EL layer 8)
Next, the organic EL layer 8 will be described. Each region constituting the organic EL layer 8 includes both charge transporting materials. The charge transporting materials are classified into low molecular materials and high molecular materials. Specific examples thereof include low molecular weight materials such as bis (carbazoyl) benzodifuran (CZBDF), derivatives of benzofuran such as diphenylaminobenzodifuran (DPABDF), cyclopentadiene derivatives, tetraphenylbutadiene derivatives, triphenylamine derivatives. , Oxadiazole derivatives, bathophenanthroline derivatives, pyrazoloquinoline derivatives, styrylbenzene derivatives, styrylarylene derivatives, aminostyryl derivatives, silole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, coumarin derivatives , Rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazoline derivatives, trifumanyl Miner derivatives, anthracene derivatives, diphenylanthracene derivatives, pyrene derivatives, carbazole derivatives, oxadiazole dimers, vilazoline dimers, triterpyridylbenzene (TbpyB), aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazole zinc complexes, benzothiazole zinc Complex, azomethylzinc complex, porphyrin zinc complex, eurobium complex, iridium complex, platinum complex, etc., Al, zinc (Zn), beryllium (Be), Pt, Ir, terbium (Tb), europium (Eu), or dysprosium ( Dy) as a central metal, and a metal complex having an oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, or quinoline structure as a ligand Etc. The.

  Polymer materials include poly (oxadiazole) (Poly-OXZ), polystyrene derivative (PSS), polyaniline-camphor sulfonic acid (PANI-CSA), poly (triphenylamine-oxadiazole) derivative ( Poly-TPD-OXD) or poly (carbazole-triazole) derivative (Poly-Cz-TAZ).

In order to obtain high luminous efficiency, it is preferable to use a dual charge transporting material having a singlet excitation level (S ₁ ) higher than the triplet excitation level (T ₁ ) of the organic light emitting material. That is, it is more preferable that the relationship of S ₁ > T ₁ is established. Thus, the excitation energy can be confined in the phosphorescent material. Therefore, it is preferable to use a carbazole group, a triazole group, a benzofuran group, or the like having a high excitation level and a high hole mobility for the both charge transporting materials.

The light emitting region 101 in the organic EL layer 8 is doped with an organic light emitting material. As this material, a known organic light emitting material for organic EL elements can be used. Specific examples thereof include fluorescent materials such as styryl derivatives, perylenes, iridium complexes, coumarin derivatives, lumogen F red, dicyanomethylenepyran, phenoxazone, or porphyrin derivatives, bis [(4,6-difluorophenyl) -pyridinato-N. , C2 ′] picolinate iridium (III) (FIrpic), tris (2-phenylpyridyl) iridium (III) (Ir (ppy) ₃ ), tris (1-phenylisoquinoline) iridium (III) (Ir (piq) ₃ ) Or phosphorescent organometallic complexes such as tris (biphenylquinoxalinato) iridium (III) (Q3Ir). Of these, phosphorescent materials are preferably used for the purpose of dramatically reducing power consumption.

(Outline of edge cover 5)
The edge cover 5 is provided between the organic EL elements 7. Note that a part of the edge cover 5 is formed so as to cover a part of the peripheral edge of the patterned anode 4. Therefore, the region where the edge cover 5 is not provided on the anode 4 is the organic EL element 7. Since the edge cover 5 is provided so as to cover the peripheral portion of the anode 4, the organic EL layer 8 is thinned or electric field concentration occurs at the peripheral portion, so that the anode 4 and the cathode 9. Can be prevented from short-circuiting.

  Examples of the material constituting the edge cover 5 include an inorganic material such as silicon oxide or silicon nitride, an organic resin material such as an acrylic resin, a polyimide resin, a photosensitive sol-gel material, or a novolac resin. Examples of the acrylic resin include an optomer series manufactured by JSR Corporation. Examples of the polyimide resin include Toray's Photo Nice series.

(Method for manufacturing organic EL display device 10)
Below, the manufacturing method of the organic electroluminescence display 10 is demonstrated with reference to FIG. FIG. 3A is a view showing a cross section of the organic EL element 7 before the annealing treatment. FIG. 3B is a view showing a cross section of the organic EL element 7 after the annealing treatment. Below, the manufacturing method of the organic EL display device 10 will be described using a specific example, but the manufacturing method of the organic EL display device 10 according to the present embodiment is not limited to this.

First, a plurality of TFTs 2 for driving organic EL elements are formed on the insulating substrate 1. As a method for forming the TFT 2, a method of ion doping impurities into amorphous silicon formed by a plasma induced chemical vapor deposition (PECVD) method, a low pressure chemical vapor deposition (LPCVD) method using a silane (SiH ₄ ) gas, and the like. Amorphous silicon is formed by a method, and after the amorphous silicon is crystallized by a solid phase growth method to obtain polysilicon, a known forming method such as ion doping by an ion implantation method may be used.

  Next, an interlayer insulating film 3 is formed in order to flatten the unevenness of the TFT 2. An example in which an acrylic resin is used as the interlayer insulating film 3 is shown below. First, a photosensitive positive acrylic resin material is applied onto the insulating substrate 1 on which the TFT 2 is formed by spin coating. After coating, the insulating substrate 1 is prebaked at 80 ° C. for 3 minutes to obtain an acrylic film (interlayer insulating film 3). Thereafter, the acrylic film at the portion where the terminal of the TFT 2 and the anode 4 are electrically connected is removed by photolithography, and post-baked at 220 ° C. for 1 hour. In this way, an interlayer insulating film 3 having contact holes is formed. The film thickness of the interlayer insulating film 3 is preferably about 1 μm.

Next, the anode 4 is formed (first electrode forming step). An example in which a V ₂ O ₅ electrode is used as the anode 4 is shown below. A V ₂ O ₅ thin film is formed by patterning V ₂ O ₅ on the insulating substrate 1 on which the interlayer insulating film 3 is formed. In this way, a V ₂ O ₅ electrode (anode 4) is formed. The film thickness of the anode 4 is preferably about 150 nm. In the present embodiment, the anode 4 is formed by a vapor deposition method, but may be formed by another dry process such as a high-frequency magnetron sputtering method or a wet process such as an inkjet method.

  Subsequently, the edge cover 5 is formed. An example using a polyimide resin as the edge cover 5 is shown below. First, a photosensitive positive polyimide resin material is applied onto the insulating substrate 1 on which the anode 4 is formed by spin coating. After coating, the insulating substrate 1 is pre-baked at 100 ° C. for 3 minutes to obtain a polyimide film (edge cover 5). Thereafter, the polyimide film on the anode 4 is removed by photolithography and post-baked at 220 ° C. for 1 hour. In this way, the edge cover 5 is formed. In addition, it is preferable that the film thickness of the edge cover 5 is about 1.5-2.0 micrometers.

Next, the organic EL layer 8 is formed. Hereinafter, an example in which bis (carbazoline) benzodifuran (CZBDF) is used as the charge transporting material and tris (2-phenylpyridyl) iridium (III) (Ir (ppy) ₃ ) is used as the organic light emitting material will be described.

First, CZBDF is vapor-deposited in a region from the anode 4 to 40 nm to form both charge transporting regions (first host regions) 103 (first host region forming step). Thereafter, CZBDF and Ir (ppy) ₃ are co-evaporated in a region from the region where CZBDF is deposited to 20 nm to form a light emitting region 101 (light emitting region forming step). At this time, Ir (ppy) ₃ is doped to about 6 wt% in CZBDF. Then, CZBDF is vapor-deposited in a region from the region where CZBDF and Ir (ppy) ₃ are co-evaporated to 40 nm to form both charge transporting regions (second host regions) 103 (second host region forming step) ). According to this configuration, as shown in FIG. 3A, the light emitting region 101 doped with the organic light emitting material is formed in the range of 20 nm in the center of the organic EL layer 8. Both the charge transporting regions 103 above and below the light emitting region 101 are not doped with an organic light emitting material.

  Subsequently, the cathode 9 is formed on the organic EL layer 8 (second electrode forming step). An example using Al as the cathode 9 is shown below. An Al electrode (cathode 9) is deposited on the organic EL layer 8 at a deposition rate of about 2 nm / sec. In this way, the cathode 9 is formed. The film thickness of the cathode 9 is preferably about 1000 nm.

Next, the hole transport region 100 and the electron transport region 102 are formed. First, the obtained insulating substrate 1 is placed on a hot plate and annealed at a constant temperature in a temperature range that does not exceed the glass transition temperature (Tg) of the organic EL layer 8. By performing annealing treatment, V ₂ O ₅ constituting the anode 4 is thermally diffused into both charge transport regions 103 adjacent to the anode 4 to form the hole transport region 100 (first carrier transport region formation step) ). Specifically, the V ₂ O ₅ concentration with respect to CZBDF is 100 wt% just above the anode 4, and annealing treatment is performed until the V ₂ O ₅ concentration becomes 0 wt% at a position 40 nm from the anode 4, and V ₂ the O ₅ is thermally diffused. More specifically, just above the anode 4 as a base point, between which the end point position of 40nm away from the anode _4, as V 2 _{O 5} concentration is linearly reduced to 0 wt% of 100 wt%, _{V 2} the O ₅ is thermally diffused.

  Similarly, by performing an annealing process, Al constituting the cathode 9 is thermally diffused into the charge transport regions 103 adjacent to the cathode 9 to form the electron transport region 102 (second carrier transport region forming step). ). Specifically, the Al concentration with respect to CZBDF is 0 wt% just above the light emitting region 101, and annealing treatment is performed until the Al concentration reaches 100 wt% at a position 40 nm away from the light emitting region 101 to thermally diffuse Al. Let More specifically, Al is heated so that the Al concentration increases linearly from 0 wt% to 100 wt% while the end point is a position 40 nm away from the light emitting area 101, with the base point being just above the light emitting area 101. Spread. In this way, as shown in FIG. 3B, annealing is performed until the hole transport region 100 and the electron transport region 102 are formed.

  Finally, the insulating substrate 1 is sealed. The sealing substrate is bonded to the insulating substrate 1 from above the cathode 9 via an ultraviolet curable resin. Then, the UV curable resin is cured by irradiating UV light of 6000 mJ with a UV lamp, and the insulating substrate 1 is sealed with the sealing substrate. In this way, the organic EL display device 10 is formed.

  As described above, according to the present embodiment, the organic EL display device 10 including the display unit in which the organic EL element 7 is formed on the thin film transistor substrate is realized.

  Moreover, according to this embodiment, the respective dopants constituting both electrodes can be diffused into both charge transporting materials by annealing, and strict concentration control can be performed. As a result, the carrier injection property / transport property of the organic EL element 7 can be improved.

  Furthermore, in this embodiment, since the annealing process can be performed under vacuum, the dopant concentration can be controlled to a desired concentration under strict temperature control. In addition, the manufacturing method of the organic EL element 7 according to the present embodiment is very simple and does not require a manufacturing apparatus such as a complicated vapor deposition apparatus, so that the manufacturing cost can be reduced.

[Second Embodiment]
(Outline of organic EL display device 10a)
The organic EL display device 10 a according to the present embodiment has a transparent electrode 4 ′ in addition to the anode 4. Except this point, the configuration is the same as that of the organic EL display device 10 according to the first embodiment. An outline of the organic EL display device 10a according to the present embodiment will be described with reference to FIGS. FIG. 4 is a view showing a cross section of the organic EL display device 10a according to the present embodiment. FIG. 5 is a diagram showing a cross section of the organic EL element 7a and the concentration of each material constituting the organic EL element 7a.

  As shown in FIG. 4, the organic EL display device 10 a includes an insulating substrate 1, a TFT 2, an interlayer insulating film 3, a transparent electrode 4 ′, an anode 4, an edge cover 5, an organic EL layer 8, and a cathode 9. Yes. A plurality of TFTs 2 are formed on the insulating substrate 1 at a predetermined interval, and a flattened interlayer insulating film 3 is disposed on the TFTs 2. A contact hole is formed in the interlayer insulating film 3, and the terminal of the TFT 2 is electrically connected to the transparent electrode 4 'through the contact hole. On the transparent electrode 4 ′, an anode 4 is formed at a position facing the TFT 2. Further, an organic EL layer 8 and a cathode 9 are formed on the anode 4. The insulating substrate 1, the transparent electrode 4 ', the anode 4, the organic EL layer 8, and the cathode 9 constitute an organic EL element 7a. An edge cover 5 is provided between the organic EL elements 7a.

  Note that the anode 4, the organic EL layer 8, and the cathode 9 according to the present embodiment constitute a single layer containing both charge transporting materials as in the first embodiment. As shown in FIG. 5, the organic EL element 7a is obtained by forming a single layer having an anode 4, an organic EL layer 8, and a cathode 9 on an insulating substrate 1 having a transparent electrode 4 '. In this figure, the TFT 2 and the interlayer insulating film 3 are omitted. In the organic EL layer 8, the acceptor material and the donor material are doped with a concentration gradient as in the first embodiment. As the transparent electrode 4 ', an electrode made of a light-transmitting conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) can be used.

As described above, the organic EL display device 10 a according to this embodiment has the transparent electrode 4 ′ in addition to the anode 4. In the first embodiment, when V ₂ O ₅ is used as the anode 4, the film thickness is as thick as about 150 nm. Therefore, the transmittance in the visible light region at the anode 4 is as low as about 20%, and it may be difficult to extract the light emitted from the organic EL element 7a from the insulating substrate 1 side. Therefore, in the present embodiment, a transparent electrode 4 ′ having a high visible light transmittance is used as the electrode. For example, when an ITO electrode is used as the anode 4 ', the transmittance of the anode 4' in the visible light region is as high as about 90%. 'The ITO electrode was formed in a thickness of about 120nm as, the transparent electrode 4' transparent electrode 4 when the _V 2 _{O 5} as an anode 4 were laminated in a thickness of about 30 nm, the transmittance of the visible light region is 60% Become. Compared with the case where the anode 4 is composed of only V ₂ O ₅ , the transmittance in the visible light region is tripled, and the extraction efficiency of light emitted from the organic EL element 7 a can be improved. At the same time, since efficient injection and transport properties of holes and electrons are maintained, low voltage driving of the organic EL display device 10a can be maintained.

(Method for manufacturing organic EL display device 10a)
Below, the manufacturing method of the organic electroluminescence display 10a is demonstrated. The organic EL display device 10a is the same as the manufacturing method of the organic EL display device 10 according to the first embodiment except that the transparent electrode 4 ′ is formed in addition to the anode 4, and here, the transparent electrode 4 ′ and Only the method for forming the anode 4 will be described.

First, a transparent electrode 4 ′ is formed. An example in which an ITO electrode is used as the transparent electrode 4 ′ is shown below. An insulating substrate on which an ITO thin film and an interlayer insulating film 3 are formed by a high-frequency magnetron sputtering method using an ITO doped with 5 wt% tin oxide as a target and Ar introduced with 1% oxygen (0 ₂ ) as a sputtering gas A pattern is formed on 1. In this way, an ITO electrode (transparent electrode 4 ′) is formed. In this way, the transparent electrode 4 ′ is formed. The film thickness of the transparent electrode 4 ′ is preferably about 120 nm. In the present embodiment, the transparent electrode 4 ′ is formed by a sputtering method, but may be formed by other dry processes such as a vacuum deposition method, or a wet process such as an inkjet method.

Next, the anode 4 is formed. An example in which a V ₂ O ₅ electrode is used as the anode 4 is shown below. A V ₂ O ₅ thin film is formed by patterning V ₂ O ₅ on the insulating substrate 1 on which the transparent electrode 4 ′ is formed. In this way, a V ₂ O ₅ electrode (anode 4) is formed. The film thickness of the anode 4 is preferably about 30 nm. In the present embodiment, the anode 4 is formed by a vapor deposition method, but may be formed by another dry process such as a high-frequency magnetron sputtering method or a wet process such as an inkjet method. Since the subsequent manufacturing steps are the same as those in the first embodiment, they are omitted here.

  In the present embodiment, the transparent electrode 4 ′ is formed so as to be in contact with the surface opposite to the surface in contact with the organic layer 8 in the anode. However, the present invention is not limited thereto, and the transparent electrode 4 ′ may be formed on the surface of the cathode 9 opposite to the surface in contact with the organic layer 8. That is, the transparent electrode 4 'may be formed on at least one of the anode side and the cathode side. Preferably, it may be provided as an electrode on the light extraction side.

  In the two embodiments described above, the formation of the hole transport region 100 in the organic EL layer 8 can be realized by the same vapor deposition process following the formation of the anode 4. That is, the anode 4 and the organic EL layer 8 are formed as the same layer, not as separate layers. Similarly, in the two embodiments described above, following the formation of the electron transport region 102, the cathode 9 can be formed by the same vapor deposition process. That is, the organic EL layer 8 and the cathode 9 are formed as the same layer, not as separate layers. Therefore, since the layer configuration in the organic EL elements 7 and 7a is simplified, the manufacturing cost of the organic EL element 7 can be greatly reduced.

[Third embodiment]
(Outline of organic EL display device 10b)
In the two embodiments described above, the organic EL layer 8 contains CZBDF as both charge transport materials. That is, the organic EL layer 8 has a homojunction structure. However, the organic EL layer 8 may have a so-called heterojunction structure in which a plurality of different hosts are included as separate layers.

  In the organic EL display device 10b according to the present embodiment, the organic EL layer (organic layer) 8a has a heterojunction structure. Except this point, the configuration is the same as that of the organic EL display device 10 according to the first embodiment. An outline of the organic EL display device 10b according to the present embodiment will be described with reference to FIGS. FIG. 6 is a view showing a cross section of the organic EL display device 10b according to the present embodiment. FIG. 7 is a diagram showing a cross section of the organic EL element 7b and the concentration of each material constituting the organic EL element 7b.

  As shown in FIG. 6, the organic EL display device 10b includes an insulating substrate (substrate) 1, a TFT 2, an interlayer insulating film 3, an anode (first electrode) 4, an edge cover 5, an organic EL layer 8a, and a cathode (first electrode). 2 electrodes) 9. A plurality of TFTs 2 are formed on the insulating substrate 1 at a predetermined interval, and a flattened interlayer insulating film 3 is disposed on the TFTs 2. A contact hole is formed in the interlayer insulating film 3, and the terminal of the TFT 2 is electrically connected to the anode 4 through the contact hole. Further, an organic EL layer 8 a and a cathode 9 are formed on the anode 4. The insulating substrate 1, the anode 4, the organic EL layer 8a, and the cathode 9 constitute an organic EL element 7b. An edge cover 5 is provided between the organic EL elements 7b.

  Unlike the first embodiment, each of the anode 4, the organic EL layer 8a, and the cathode 9 according to the present embodiment is a single layer. As shown in FIG. 7, the organic EL layer 8a includes a first organic EL layer 6a and a second organic EL layer 6b. The first organic EL layer 6a has a hole transport region (first carrier transport region) 100 and a first light emitting region 101a, and the second organic EL layer 6b has an electron transport region (second carrier transport region). ) 102 and the second light emitting region 101b. The first light emitting area 101 a and the second light emitting area 101 b constitute the light emitting area 101. In this figure, the TFT 2 and the interlayer insulating film 3 are omitted.

  In the organic EL layer 8a, the acceptor material and the donor material are doped with a concentration gradient as in the first embodiment.

(Manufacturing method of the organic EL display device 10b)
Hereinafter, a method for manufacturing the organic EL display device 10b will be described with reference to FIG. FIG. 8A is a view showing a cross section of the organic EL element 7b before the annealing treatment. FIG. 8B is a view showing a cross section of the organic EL element 7b after the annealing treatment. Below, the manufacturing method of the organic EL display device 10 will be described using a specific example, but the manufacturing method of the organic EL display device 10 according to the present embodiment is not limited to this. The organic EL display device 10b is the same as the manufacturing method of the organic EL display device 10 according to the first embodiment except that the organic EL8 layer has a heterojunction structure. Only the formation method will be mentioned.

First, the organic EL layer 8a is formed. Hereinafter, an example in which diphenylaminobenzodifuran (DPABDF) and triterpyridylbenzene (TbpyB) are used as both charge transporting materials (host materials) and Ir (ppy) ₃ is used as the organic light emitting material will be described.

First, the first organic EL layer 6a is formed. Specifically, DPABDF is vapor-deposited in a region up to the anode 40 nm to form both charge transporting regions (first host regions) 103 (first host region forming step). Thereafter, DPABDF and Ir (ppy) ₃ are co-evaporated in a region from the region where DPABDF is deposited to 20 nm to form the first light emitting region 101a (light emitting region forming step). At this time, Ir (ppy) ₃ is doped to about 8 wt% in DPABDF.

Next, the second organic EL layer 6b is formed. Specifically, TbpyB and Ir (ppy) ₃ are co-evaporated in a region from 20 nm to 20 nm from the region where DPABDF and Ir (ppy) ₃ are co-evaporated to form the second light emitting region 101b (light emitting region). Forming step). At this time, Ir (ppy) ₃ is doped to about 6 wt% in TbpyB. Thereafter, TbpyB is vapor-deposited in a region from the region where TbpyB and Ir (ppy) ₃ are co-evaporated to 40 nm to form both charge transporting regions (second host regions) 103 (second host region forming step) ). According to this configuration, as shown in FIG. 8A, the light emitting region 101 having a film thickness of 40 nm is formed by the range of 40 nm in the center of the organic EL layer 8a, that is, the first light emitting region 101a and the second light emitting region 101b. Has been. The region from the light emitting region 101 to the upper and lower 40 nm is not doped with an organic light emitting material. In the above, an example in which the concentration of doping the organic light emitting material is different between the first light emitting region 101a and the second light emitting region 101b has been described, but the present invention is not necessarily limited thereto. In view of electrical characteristics such as carrier mobility or energy level of the host material used, the doping concentration of the organic light emitting material in the first light emitting region 101a and the second light emitting region 101b may be the same.

  Subsequently, the cathode 9 is formed on the organic EL layer 8a. An example using Al as the cathode 9 is shown below. An Al electrode (cathode 9) is deposited on the organic EL layer 8 at a deposition rate of about 2 nm / sec. In this way, the cathode 9 is formed (second electrode forming step). The film thickness of the cathode 9 is preferably about 1000 nm.

Next, the hole transport region 100 and the electron transport region 102 are formed. First, the obtained insulating substrate 1 is placed on a hot plate and annealed at a constant temperature in a temperature range that does not exceed the glass transition temperature (Tg) of the organic EL layer 8. By performing annealing treatment, V ₂ O ₅ constituting the anode 4 is thermally diffused into both charge transport regions 103 adjacent to the anode 4 to form the hole transport region 100 (first carrier transport region formation step) ). Specifically, in just on the anode 4 becomes 100 wt% concentration of _V 2 _{O 5} with respect DPABDF, at the position of 40nm from the anode _4, an annealing process to V 2 _{O 5} concentration of 0 wt%, _{V 2} the O ₅ is thermally diffused. More specifically, just above the anode 4 as a base point, between which the end point position of 40nm away from the anode _4, as V 2 _{O 5} concentration is linearly reduced to 0 wt% of 100 wt%, _{V 2} the O ₅ is thermally diffused.

  Similarly, by performing an annealing process, Al constituting the cathode 9 is thermally diffused into the charge transport regions 103 adjacent to the cathode 9 to form the electron transport region 102 (second carrier transport region forming step). ). Specifically, the Al concentration with respect to DPABDF is 0 wt% just above the light emitting region 101, and at a position 40 nm away from the light emitting region 101, annealing is performed until the Al concentration reaches 100 wt% to thermally diffuse Al. Let More specifically, Al is heated so that the Al concentration increases linearly from 0 wt% to 100 wt% while the end point is a position 40 nm away from the light emitting area 101, with the base point being just above the light emitting area 101. Spread. In this manner, as shown in FIG. 8B, annealing is performed until the hole transport region 100 and the electron transport region 102 are formed.

  Finally, the insulating substrate 1 is sealed. The sealing substrate is bonded to the insulating substrate 1 from above the cathode 9 via an ultraviolet curable resin. Then, the UV curable resin is cured by irradiating UV light of 6000 mJ with a UV lamp, and the insulating substrate 1 is sealed with the sealing substrate. In this way, the organic EL display device 10b is formed.

  As described above, according to the present embodiment, the organic EL display device 10b including the display unit in which the organic EL element 7 is formed on the thin film transistor substrate is realized.

In the organic EL display device 10b according to the present embodiment, an acceptor (first dopant) is doped on the anode side (hole transport layer 100) of the first organic EL layer 6a, and the cathode side of the second organic EL layer 6b. The (electron transport layer 102) is doped with a donor (second dopant). As a result, the band structure of the organic EL layer 8a changes and the carrier concentration increases, so that the injection efficiency and conductivity of holes (first carriers) and electrons (second carriers) are improved.
As a result, the hole injecting layer and the electron injecting layer are not necessary, the carrier conductivity is improved, and the light emitting region 101 has sufficient conductivity for transporting holes and electrons. Thus, the hole transport region 100 and the light emitting region 101 can be shared. Similarly, the electron transport region 102 and the light emitting region 101 can be shared.

  Furthermore, in the organic EL display device 10b according to the present embodiment, the first organic EL layer 6a and the second organic EL layer 6b are stacked, and an organic light emitting material is doped in the vicinity of the interface between the two organic EL layers. Thus, carriers can be confined in the first light emitting region 101a and the second light emitting region 101b (near the interface between both organic EL layers) due to the difference in the mobility of holes and electrons in each layer. As a result, the probability of recombination of holes and electrons can be improved, and high luminous efficiency can be obtained. In addition, since the balance of the carrier can be maintained, light emission with high luminance can be provided.

  In addition, since carriers can be confined in the light-emitting region 101, the balance between holes and electrons is not lost due to a difference in hole mobility and electron mobility due to aging. Therefore, it is possible to solve problems relating to lifetime such as a decrease in luminous efficiency and color shift.

  Since the organic EL layer 8a has a two-layer structure of the first organic EL layer 6a and the second organic EL layer 6b, the layer configuration is very simple. Therefore, for example, in the current mainstream cluster-type manufacturing method in which each layer is formed in a separate vapor deposition chamber, it can be produced with only two vapor deposition chambers. On the other hand, in a conventional organic EL device composed of six layers, six vapor deposition chambers are necessary for production. Therefore, according to the present embodiment, the organic EL element 7b can be manufactured with an initial investment amount of 1/3 compared with the initial investment amount when manufacturing the conventional organic EL element. In addition, although the structure which the organic EL layer 8a has a two-layer structure was demonstrated above, it is not necessarily limited to this. For example, the hole transport region 100, the light emitting region 101, and the electron transport region 102 may be configured as single layers.

  In the present embodiment, a transparent electrode 4 ′ may be provided in addition to the anode 4 as in the second embodiment. Thereby, the extraction efficiency of the light emitted from the organic EL element 7b can be improved. At the same time, since efficient injection and transport properties of holes and electrons are maintained, low voltage driving of the organic EL display device 10b can be maintained. The transparent electrode 4 'may be formed on at least one of the anode side and the cathode side. Preferably, it may be provided as an electrode on the light extraction side.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  For example, in the three embodiments described above, the anode 4 is formed by an acceptor, and the cathode 9 is formed by a donor. However, in the present invention, at least one of the pair of electrodes (the anode 4 and the cathode 9) is formed of the same material as the dopant that promotes the transport of carriers injected into the organic EL layer 8 by the electrode. All you need is it. Thereby, since at least one of two kinds of carriers (holes or electrons) can be efficiently injected and transported, the driving voltage of the organic EL element 7 can be lowered.

  Further, in the above-described three embodiments, the annealing process is performed after the cathode 9 is formed. However, for example, there is no problem if the annealing process is performed after the insulating substrate 1 is sealed. Further, in the manufacturing methods according to the above-described three embodiments, annealing is performed and the acceptor and the donor are thermally diffused. However, the present invention is not necessarily limited thereto. For example, after forming the host region 103 on the anode 4 side or the organic EL layer 8a, annealing may be performed to thermally diffuse the acceptor. After that, the cathode 9 may be formed and annealed to diffuse the donor. In this way, it is possible to change the order in which the annealing process is performed at any time.

  In addition, after forming the cathode 9 or sealing the insulating substrate 1, annealing is performed in a state where a voltage is applied to the organic EL elements 7, 7 a, 7 b, thereby improving the diffusion rate of the dopant and annealing treatment. It is thought that the time required for this will be shortened. Therefore, a voltage may be applied to the organic EL elements 7, 7a, 7b during the annealing process.

  In the above-described three embodiments, the insulating substrate 1 is placed on a hot plate for annealing treatment. However, annealing treatment using an oven, annealing treatment under reduced pressure using a vacuum oven, or infrared annealing is also used. It goes without saying that other annealing treatments such as treatment can also be applied.

  The present invention can be used for various devices using organic EL elements, and can be used for display devices such as televisions.

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Thin-film transistor 3 Interlayer insulating film 4 Anode 4 'Transparent electrode 5 Edge cover 6a 1st organic electroluminescent layer 6b 2nd organic electroluminescent layer 7, 7a, 7b, 20, 20a Organic electroluminescent element 8, 8a Organic Electroluminescence layer 9 Cathode 10, 10a, 10b Organic electroluminescence display device 11 Substrate 12 Anode 13 Hole injection layer 14 Hole transport layer 15 Light emitting layer 16 Hole blocking layer 17 Electron transport layer 18 Electron injection layer 19 Cathode 100 Hole Transport region 101 Light-emitting region 101a First light-emitting region 101b Second light-emitting region 102 Electron transport region 103 Dual charge transporting region 200 Acceptor region 201 Light-emitting region 202 Donor region

Claims (11)

A first electrode and a second electrode;
A method for producing an organic electroluminescent element comprising an organic layer formed between the first electrode and the second electrode and having at least a light emitting region doped with an organic light emitting material on a substrate,
On the substrate, a first electrode forming step of forming the first electrode composed of a first dopant that promotes transport of a first carrier injected from the first electrode into the organic layer;
A first host region forming step of forming a first host region made of a predetermined host material on the first electrode;
On the first host region, a light emitting region forming step of forming the light emitting region in which a predetermined host material is doped with the organic light emitting material;
A second host region forming step of forming a second host region made of a predetermined host material on the light emitting region;
A second electrode forming step of forming the second electrode on the second host region;
After the first host region forming step, by heating the substrate, a first carrier transport region forming step for forming a first carrier transport region for transporting the first carrier in the first host region, A method for producing an organic electroluminescence element, comprising: In the second electrode formation step, the second electrode is formed of a dopant that promotes transport of second carriers injected from the second electrode into the organic layer,
A second carrier transport region forming step of forming a second carrier transport region for transporting the second carrier in the second host region by heating the substrate after the second electrode forming step; The manufacturing method of the organic electroluminescent element of Claim 1 characterized by the above-mentioned. A first electrode and a second electrode;
A method for producing an organic electroluminescent device comprising, on a substrate, an organic layer formed between the first electrode and the second electrode and having at least an organic layer doped with an organic light emitting material.
A first electrode forming step of forming the first electrode on the substrate;
A first host region forming step of forming a first host region made of a predetermined host material on the first electrode;
On the first host region, a light emitting region forming step of forming the light emitting region in which a predetermined host material is doped with the organic light emitting material;
A second host region forming step of forming a second host region made of a predetermined host material on the light emitting region;
A second electrode forming step of forming the second electrode on the second host region with a dopant that promotes transport of a second carrier injected from the second electrode into the organic layer;
After the second electrode forming step, there is provided a second carrier transport region forming step for forming a second carrier transport region for transporting the second carrier in the second host region by heating the substrate. A method for producing an organic electroluminescent element, characterized by comprising:   The method for producing an organic electroluminescence element according to claim 2, wherein the first carrier transport region forming step and the second carrier transport region forming step are simultaneously performed. Performing the first carrier transport region forming step after the second electrode forming step;
3. The method of manufacturing an organic electroluminescence element according to claim 1, wherein a voltage is applied to the first electrode and the second electrode in the first carrier transport region forming step.   5. The method of manufacturing an organic electroluminescence element according to claim 2, wherein a voltage is applied to the first electrode and the second electrode in the second carrier transport region forming step.   3. The method of manufacturing an organic electroluminescence element according to claim 1, wherein in the first carrier transport region forming step, the substrate is heated at a temperature not exceeding a glass transition temperature of the substrate.   The said 2nd carrier transport area | region formation process WHEREIN: The said board | substrate is heated at the temperature which does not exceed the glass transition temperature of the said board | substrate, The manufacture of the organic electroluminescent element of any one of Claims 2-4 characterized by the above-mentioned. Method.   In the said 1st electrode formation process, a transparent electrode is formed on the said board | substrate, and the said 1st electrode is formed on the said transparent electrode, The organic electro of any one of Claims 1-8 characterized by the above-mentioned. Manufacturing method of luminescence element.   In the said 2nd electrode formation process, a transparent electrode is formed on the said board | substrate, and the said 2nd electrode is formed on the said transparent electrode, The organic electro of any one of Claims 1-8 characterized by the above-mentioned. Manufacturing method of luminescence element. In the first host region forming step, the first host region made of both charge transport materials is formed,
In the light emitting region forming step, the light emitting region is formed by doping the organic light emitting material into the same charge transporting material as the both charge transporting material constituting the first host region,
In the second host region forming step, the first host region made of the same charge transporting material as the both charge transporting materials constituting the first host region is formed. 10. The method for producing an organic electroluminescence element according to any one of 10 above.

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