JP2007265659A - Manufacturing method of organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of forming a structure for disturbing a reflection angle of a reflective electrode for improving extraction efficiency of light with high precision and productivity. <P>SOLUTION: The manufacturing method for arranging the organic EL element 9 on a translucent substrate 1 wherein the organic El element 9 is formed by sandwiching a functional organic layer 8 formed of a plurality of layers including a light emitting layer 4 between a translucent electrode 2 formed of a translucent conductive material and a reflective electrode 7 having a structure for disturbing the reflection angle, includes a process for forming an uneven part on, for example, a hole transport layer 3 which is at least one layer of the functional organic layer 8. In the process, a projected part 3a is formed by partially vaporizing the hole transport layer 3 of the functional organic layer 8 by using laser process, electron beam lithography, or ion beam process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, a functional organic layer having at least a light emitting layer is sandwiched between a translucent electrode made of a translucent conductive material and a reflective electrode having a structure that disturbs the reflection angle on a translucent substrate. More particularly, the present invention relates to a method for manufacturing an organic EL panel that improves luminous efficiency.

  In a self-luminous display device such as an organic EL element, when light emitted from a light emitting layer is extracted to the outside, the refractive index of an organic film composed of a plurality of layers such as a substrate, a translucent electrode, and a light emitting layer is unique. It is known that light having a total reflection critical angle that is determined by the total reflection is totally reflected and lost as guided light and cannot be extracted outside. Also, in the case of an organic EL element using a reflective electrode (for example, an aluminum electrode) as the back electrode on the second electrode side, light is emitted from the light emitting layer and directly taken out from the translucent electrode on the first electrode side. In light and light extracted outside via reflection at the reflective electrode, similarly, light exceeding the total reflection critical angle is lost as guided light, and only about 20% of the total light can be extracted outside. It has been known. (For example, see "Organic EL Handbook" issued by Realize Science and Technology Center).

  If the above-mentioned ratio of emitted light that can be extracted to the outside of only about 20% (hereinafter referred to as light extraction efficiency) can be improved, the brightness of displays, instrument displays, lighting devices, etc. using organic EL elements Is expected to dramatically increase, and various research and development is being carried out in various places. In this way, the light extraction efficiency can be improved by, for example, reducing the output current capacity of the driving IC by half if the efficiency can be doubled (that is, about 40%) as compared to the current level, and the electrode used for the wiring. It is possible to reduce the wiring width, organic EL panel application and manufacturing cost, such as downsizing the display module, increasing the number of elements that can be formed on a glass substrate of the same area, and reducing the cost of the drive IC used Expectation from is also great.

In order to improve the light extraction efficiency, Patent Document 1 and Patent Document 2 propose a structure that disturbs the reflection angle of the reflective electrode (back electrode). That is, Patent Document 1 condenses the reflected light as light in order to extract the guided light to the outside by making the reflective electrode into a tapered shape, and Patent Document 2 reflects the reflected light by using a micro projection on the reflective electrode. A structure for improving the light extraction efficiency by condensing a part of the light by scattering is disclosed. In order to improve the light extraction efficiency by another method, an unevenness is formed in the first layer (hole transport layer) of the organic layer using a solvent, and then the second and subsequent organic layers and Japanese Patent Application Laid-Open No. H10-228667 discloses forming an unevenness by sequentially forming reflective electrodes. Another method for improving the light extraction efficiency by another method is disclosed in Patent Document 3. In Patent Document 3, the first layer (hole transport layer) of the organic layer is formed in a concavo-convex shape using a vapor deposition mask having holes at predetermined positions, and then the second and subsequent organic layers and reflections are formed. Disclosed are those in which irregularities are formed by sequentially forming conductive electrodes, and those in which irregularities are formed and formed in the first layer (hole transport layer) of the organic layer using a solvent.
JP-A-10-189243 JP-A-11-214162 JP-A-17-228501

  However, Patent Document 3 uses a vapor deposition mask, but it is very difficult to accurately adjust the deformation and variation of the concavo-convex shape due to the performance of the vapor deposition apparatus at the optical wavelength level. At present, it is very difficult to form the unevenness at the optical wavelength level with high accuracy and high productivity. In addition, in the manufacturing method disclosed in Patent Document 3, the control of the uneven shape is determined by the so-called “wetability” determined by the translucent electrode, the organic material (solute), and the cohesive energy of the solution. The intended shape such as uneven steps and uneven pitches cannot be accurately formed, and it is difficult to manufacture a process using a solvent in the middle of a vacuum deposition process that dislikes moisture and solvent, and organics due to the remaining solvent There is concern about the performance degradation of the layer. As described above, in reality, there is no practical method for forming a structure that disturbs the reflection angle of the reflective electrode that has both accuracy and productivity.

  The present invention is made in view of the above-described problems, and provides a manufacturing method capable of forming a structure that disturbs the reflection angle of a reflective electrode capable of improving the light extraction efficiency with high accuracy and high productivity. With the goal.

  In order to solve the above-mentioned problems, the present invention provides a translucent functional organic layer comprising a plurality of light-emitting layers on a translucent substrate as in the method for producing an organic EL panel according to claim 1. A method for producing an organic EL panel comprising an organic EL element sandwiched between a translucent electrode made of a conductive conductive material and a reflective electrode having a structure that disturbs the reflection angle, Forming a concavo-convex surface on at least one layer of the functional organic layer, and the step partially includes at least one layer of the functional organic layer using laser processing, electron beam lithography, or ion beam processing. Vaporized to form convex portions or concave portions.

  In the present invention, a functional organic layer having at least a light emitting layer is sandwiched between a translucent electrode made of a translucent conductive material and a reflective electrode having a structure that disturbs the reflection angle on a translucent substrate. The structure for disturbing the reflection angle of the reflective electrode capable of improving the light extraction efficiency of the organic EL element with high accuracy and productivity Can be well formed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, an organic EL panel A includes a translucent electrode (anode) 2 as a first electrode, a hole transport layer 3, and a light emitting layer on a translucent substrate 1 made of a translucent glass material. 4, an electron transport layer 5, an electron injection layer 6, and a reflective electrode (cathode) 7 as a second electrode are sequentially formed. A hole transport layer 3, a light emitting layer 4, an electron transport A functional organic layer 8 is constituted by the layer 5 and the electron injection layer 6, and an organic EL element 9 is constituted by the translucent electrode 2, the functional organic layer 8 and the reflective electrode 7.

  The translucent electrode 2 is formed by layering a translucent conductive material such as ITO (Indium Tin Oxide) on the support substrate 1 by a method such as sputtering or vapor deposition, and for example, stripes by a photolithography method. It is formed by patterning.

  The organic layer 8 is formed by sequentially laminating a hole transport layer 3, a light emitting layer 4, an electron transport layer 5 and an electron injection layer 6 by means of vapor deposition or the like, and has a layer shape with a film thickness of about 80 to 280 nm. is there.

  The hole transport layer 3 has a function of capturing holes from the translucent electrode 2 and transmitting the holes to the light emitting layer 4. For example, a hole transport material having a high hole mobility such as an amine-based compound is used for vapor deposition. It is formed in a layered form with a film thickness of about 20 to 80 nm by means.

  The light-emitting layer 4 is formed by doping a host material with at least a fluorescent material as a guest material by means of vapor deposition or the like to form a layer having a thickness of about 20 to 60 nm. The host material can transport holes and electrons, and has a function of emitting light when the holes and electrons are transported and recombined. For example, the host material includes a distyrylarylene derivative. The fluorescent material has a function of emitting light in response to recombination of electrons and holes, and exhibits a predetermined emission color, for example, BD102 manufactured by Idemitsu Kosan Co., Ltd., which exhibits blue-green emission.

  The electron transport layer 5 has a function of transmitting electrons to the light emitting layer 4. For example, an electron transport material having a high electron mobility such as aluminum quinolinol (Alq3) which is a chelate compound is deposited by means such as vapor deposition. It is formed in a layer shape of about 20 to 60 nm.

  The electron injection layer 6 has a function of injecting electrons from the reflective electrode 7, and is formed, for example, by forming lithium fluoride (LiF) into a layer having a thickness of about 1 nm by means such as vapor deposition.

  The reflective electrode 7 is formed by forming a conductive material such as aluminum (Al) or magnesium silver (Mg: Ag) into a layer having a thickness of about 50 to 200 nm by means such as vapor deposition.

  Next, the manufacturing method of the organic EL panel A will be described in detail with reference to FIGS.

  The hole transport layer 3 as the first layer of the functional organic layer 8 is partially vaporized by the ablation phenomenon using the laser 10 disposed in a vacuum laser processing chamber connected to a vacuum deposition apparatus (not shown). Let me. Note that the vaporized unnecessary organic matter can be prevented from being reattached to the substrate by being exhausted by a vacuum pump disposed in the vacuum deposition apparatus in a gas state.

  The laser 10 used for laser processing is preferably an excimer laser having a high excitation energy, a YAG high wavelength laser, a HeCd laser, or the like. In order to vaporize the hole transport layer 3 in a fine shape with high accuracy and eliminate the adverse thermal effects (melting, transition, crystallization, etc. due to heat) on the hole transport layer 3 to be left, a short pulse is used. Therefore, a laser species having a high excitation energy that has a low thermal contribution to the functional organic layer (organic EL element) 8 outside the processing portion (a portion to be vaporized) is preferable.

  FIG. 2 shows a state where unnecessary hole transport layers 3 other than the convex portions 3a are removed to form the convex portions 3a on the hole transport layer 3 on the translucent electrode 2 formed on the translucent electrode 1. Is shown.

  As a processing method using an excimer laser, a pulse method is effective for generating an ablation phenomenon. As the pulse width is shorter, thermal damage can be reduced and processing accuracy can be improved. Preferably, it is 100 μsec or less, more preferably 100 nanoseconds or less, still more preferably picosecond or femtosecond. For example, in the case of an argon fluoride laser (ArF), desirable processing can be obtained with a pulse energy of 210 mJ to 250 mJ and PPS (number of pulses / second) of 20 to 200, and in the case of a krypton fluoride laser (KrF), the pulse energy Desirable processing is obtained at 430 mJ to 500 mJ and PPS 25 to 200.

  As another processing method for partially removing the hole transport layer 3, an electron beam drawing method or an ion beam processing is used.

  In a processing method using electron beam irradiation (electron beam drawing method), the electron beam acceleration voltage is preferably 2 kV or more and usually 50 kV or less.

  In the processing method using an ion beam, irradiation with ion beams such as argon, oxygen, and gallium can be performed with irradiation of several hundred eV to 50 keV. However, since the processing accuracy is difficult due to the spread of the beam at low energy, Irradiation at about 10 keV to 30 keV is preferable.

  By using any of the above processing methods, the convex portion 3a can be formed of the material of the hole transport layer 3. Thereafter, the hole transport layer 3 is deposited on the convex portion 3a by a conventional vapor deposition method to form the hole transport layer 3 having the convex portion 3a, and the convex 3a and the concave portion 3b are formed on the hole transport layer 3, The second, third and fourth layers of the functional organic layer 8 are formed by sequentially depositing the light emitting layer 4, the electron transport layer 5 and the electron injection layer 6 to obtain the functional organic layer 8. By forming the reflective electrode 7 on the organic layer 8 by vapor deposition, it is possible to obtain the reflective electrode 7 having a structure including convex portions 7a and concave portions 7b that disturb the reflection angle.

  Such a method for manufacturing an organic EL panel A includes a functional organic layer 8 composed of a plurality of layers including a light emitting layer 4 on a translucent substrate 1 and a reflection angle of the translucent electrode 1 made of a translucent conductive material. In relation to a manufacturing method in which an organic EL element 9 sandwiched between a reflective electrode 7 having a structure that disturbs the structure is disposed, at least one functional organic layer 8 such as a hole transport layer 3 is uneven. And forming the convex portion 3a by partially vaporizing the hole transport layer 3 of the functional organic layer 8 using laser processing, electron beam lithography or ion beam processing. It is.

  Therefore, the hole transport layer 3 is vapor-deposited again by partially removing the accurate position by using laser processing, electron beam lithography, or ion beam processing. The reflective electrode 7 having a structure in which the reflection angle is disturbed can be obtained by sequentially forming the light emitting layer 4, the electron transport layer 5, the electron injection layer 6 and the reflective electrode 7 by forming irregularities on the surface. A structure that disturbs the reflection angle of the reflective electrode capable of improving the light extraction efficiency of the organic EL element 9 can be formed with high accuracy and high productivity.

  In the embodiment of the present invention, the concavo-convex portion is formed on the hole transport layer 3 by using laser processing, electron beam drawing, or ion beam processing. It may be formed in any one of the layers 8 by using laser processing, electron beam drawing, or ion beam processing.

  Moreover, in embodiment of this invention, in order to form the convex part 3a in the positive hole transport layer 3, the hole transport layers 3 other than the convex part 3a are removed using laser processing, an electron beam drawing method, or ion beam processing. However, it is possible to form the reflective electrode 7 having a concavo-convex structure that disturbs the reflection angle by forming the concave portion by using laser processing, electron beam lithography, or ion beam processing.

  In the embodiment of the present invention, the convex portion 3a is formed on the hole transport layer 3 and then formed again on the hole transport layer 3. However, without forming the hole transport layer 3 on the convex portion 3a, You may make it form the layer (organic layer 4) which becomes.

It is principal part sectional drawing which shows the organic electroluminescent panel of embodiment of this invention. It is a figure explaining the manufacturing method of the organic electroluminescent panel of embodiment same as the above. It is a figure explaining the organic electroluminescent panel in the manufacturing process of embodiment same as the above.

Explanation of symbols

A Organic EL Panel 1 Translucent Substrate 2 Translucent Electrode 3 Hole Transport Layer 4 Light-Emitting Layer 5 Electron Transport Layer 6 Electron Injection Layer 7 Reflective Electrode 8 Functional Organic Layer 9 Organic EL Element 10 Laser 3a, 4a, 5a , 6a, 7a Convex part

Claims (1)

A functional organic layer composed of a plurality of layers including a light emitting layer is sandwiched between a translucent electrode made of a translucent conductive material and a reflective electrode having a structure that disturbs the reflection angle on a translucent substrate. An organic EL panel manufacturing method in which an organic EL element is provided,
Forming a concavo-convex surface on at least one layer of the functional organic layer, wherein the step includes at least one layer of the functional organic layer using laser processing, electron beam lithography, or ion beam processing. The method for producing an organic EL panel is characterized by forming a convex part or a concave part by vaporizing it.

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