JP2005310590A - Organic el display device and its manufacturing method, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the emission efficiency of emitted light of an organic EL display device. <P>SOLUTION: This organic EL display device has organic functional layers 110 comprising at least luminous layers 110b in a plurality of predetermined regions (A) of a substrate 2, and performs display by emitting light L from the luminous layers 110b in a predetermined viewing direction. The device has the organic functional layers 110 in openings formed corresponding to the predetermined regions (A), and is equipped with banks 112a having translucency to the emitted light L, and reflective portions 112c for totally or partially reflecting in the viewing direction the emitted light L conducted through the banks 112a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic EL display device, a manufacturing method thereof, and an electronic apparatus.

  2. Description of the Related Art In recent years, in electronic devices such as notebook computers, mobile phones, and electronic notebooks, display devices such as an organic EL display device that includes a plurality of organic electroluminescence (hereinafter referred to as organic EL) elements corresponding to pixels as means for displaying information. Proposed. In general, an organic EL element has a configuration in which an organic functional layer including an organic EL layer (light emitting layer) is disposed between a pair of opposed electrodes.

In such an organic EL display device, various proposals have been made to improve the emission efficiency of emitted light emitted from the light emitting layer.
For example, Japanese Patent Application Laid-Open No. 10-189243 discloses a technique for improving emission efficiency of emitted light by setting a cross-sectional shape of a pixel, that is, an organic EL element in a mortar shape. Japanese Unexamined Patent Application Publication No. 21412 and Japanese Patent Application Laid-Open No. 9-171892 disclose a technique for improving emission efficiency of emitted light by forming a condensing structure of emitted light in a pixel cross-sectional structure.
JP-A-10-189243 Japanese Patent Laid-Open No. 11-214163 Japanese Patent Laid-Open No. 9-171892

However, in the technique disclosed in Japanese Patent Application Laid-Open No. 10-189243, the light emitting layer has a flat surface portion and a slope portion, so that a film member having a uniform film thickness is formed on the flat surface portion and the slope portion. It is difficult. For this reason, for example, there is a concern that the film thickness of the cathode or the like formed on the light emitting layer is not uniform.
In addition, the techniques disclosed in Japanese Patent Application Laid-Open Nos. 11-21412 and 9-171892 are difficult to realize from the viewpoint of cost and the like because it is necessary to form a complicated light collecting structure in the pixel cross-sectional structure.

  The present invention has been made in view of the above-described problems, and an object thereof is to improve the emission efficiency of emitted light.

  In order to achieve the above object, an organic EL display device of the present invention has an organic functional layer including at least a light emitting layer in a plurality of predetermined regions of a substrate, and emits light emitted from the light emitting layer in a predetermined viewing direction. An organic EL display device that performs display by emitting light to the bank, the bank having the organic functional layer in an opening formed corresponding to the predetermined region and having transparency to the emitted light And a reflecting part that reflects all or part of the emitted light guided in the bank part in the viewing direction.

  According to the organic EL display device of the present invention having such characteristics, all or a part of the emitted light guided in the translucent bank is reflected in the viewing direction by the reflecting portion. For this reason, in the conventional organic EL display device, the emitted light that has disappeared by being emitted from the emitted light to the side is reflected in the viewing direction by the reflecting portion. Therefore, according to the organic EL display device of the present invention, the emission efficiency of the emitted light can be improved, and the organic EL display device having more excellent emission characteristics can be obtained.

  In addition, the organic EL display device of the present invention can employ a configuration in which the reflecting portion is a scattering portion that scatters the emitted light. Thus, when the reflection part is a scattering part that scatters the emitted light, the emitted light emitted from the light emitting layer to the side is scattered by the scattering part, and a part of the emitted light emitted to the side Is reflected in the viewing direction.

In addition, the organic EL display device of the present invention can employ a configuration in which the scattering portion is an upper surface of the roughened bank portion.
In the conventional organic EL display device, the emitted light emitted laterally from the light emitting layer is incident on the upper surface or the lower surface of the bank portion at an angle less than the critical angle, so the upper surface or the lower surface of the bank portion. And disappeared without being emitted outside the organic EL display device. Therefore, as in the organic EL display device of the present invention, by roughening the upper surface of the bank portion, the upper surface of the bank portion functions as a scattering portion. That is, the emitted light emitted laterally from the light emitting layer is scattered by the roughened upper surface of the bank portion, and a part thereof is reflected in the viewing direction. Therefore, the emission efficiency of emitted light can be improved.
In addition, it is preferable that the surface roughness of the upper surface of the bank portion is Ra = 10 to 100 nm. Thereby, the emitted light can be scattered more efficiently, and the emission efficiency of the emitted light can be further improved.
In addition, the bottom surface of the bank can be roughened, and this bottom surface can be used as a scattering portion. However, it is difficult to roughen the bottom surface of the bank in the manufacturing process, so the top surface of the bank is rough. Is preferable.

In addition, the organic EL display device of the present invention may employ a configuration in which the scattering portion is an upper surface of the bank portion having a reflecting surface shape of the light guide plate.
For example, by making the upper surface of the bank part a Fresnel surface which is one of the reflecting surface shapes of the light guide plate, more emitted light emitted from the light emitting layer to the side can be scattered in the viewing direction. Therefore, according to the organic EL display device of the present invention that employs such a configuration, the emission efficiency of emitted light can be further improved.
In addition, although the lower surface of the bank portion can be a reflecting surface shape of the light guide plate, and this lower surface can be a scattering portion, it is difficult to make the lower surface of the bank portion a reflecting surface shape of the light guide plate because of the manufacturing process. It is preferable that the top surface of the bank portion has a reflecting surface shape of the light guide plate.

In addition, the organic EL display device of the present invention can employ a configuration having a reflective film adjacent to the upper surface of the bank portion.
By adopting such a configuration, emitted light scattered in the direction opposite to the viewing direction in the scattering portion is reflected by the reflective film and emitted in the viewing direction, so that the emission efficiency of emitted light is further improved. Can do.
In the case of an organic EL display device having a reflective electrode on the bank, the reflective electrode can function as the reflective film of the present invention.

  Next, the organic EL display device manufacturing method of the present invention has an organic functional layer including at least a light emitting layer in a plurality of predetermined regions of the substrate, and emits light emitted from the light emitting layer in a predetermined viewing direction. A method of manufacturing an organic EL display device that performs display by performing a bank portion forming step of forming a bank portion having an opening portion corresponding to the predetermined region, and the organic functional layer in the opening portion An organic functional layer forming step for forming the reflecting portion, and a reflecting portion forming step for forming a reflecting portion for reflecting all or part of the emitted light guided in the bank portion in the viewing direction.

  According to the method of manufacturing the organic EL display device of the present invention having such characteristics, the reflective portion that reflects all or part of the emitted light guided in the bank portion in the viewing direction by the reflective portion forming step. Thus, an organic EL display device with improved emission efficiency of emitted light can be manufactured.

Moreover, the manufacturing method of the organic electroluminescent display device of this invention can employ | adopt the structure that the said reflection part formation process includes the process of performing a plasma process with respect to the upper surface of the said bank part.
By adopting such a configuration, the upper surface of the bank can be easily roughened. Therefore, it is possible to easily form the upper surface of the bank portion as a reflecting portion.

  In the method for manufacturing an organic EL display device of the present invention, the reflecting portion forming step may include a wet etching step with respect to the upper surface of the bank portion. By adopting such a configuration, for example, the reflecting surface of the light guide plate can be easily formed on the top surface of the bank portion. Therefore, it is possible to easily form the upper surface of the bank portion as a reflecting portion.

Further, in the method for manufacturing an organic EL display device of the present invention, in the reflecting portion forming step, the upper surface of the bank portion is formed into a reflecting surface shape of the light guide plate by pressing a predetermined mold against the upper surface of the bank portion. A configuration including a molding step can also be employed.
By adopting such a configuration, the upper surface of the bank portion can be easily formed into the shape of the reflecting surface of the light guide plate. Therefore, it is possible to easily form the upper surface of the bank portion as a reflecting portion.

Next, an electronic apparatus according to the present invention includes the organic EL display device according to the present invention as a display unit.
According to the organic EL display device of the present invention, since the emission efficiency of emitted light is improved and the light emission characteristics are improved, an electronic apparatus including the organic EL display device of the present invention as a display unit has improved display characteristics. . Therefore, according to the electronic device of the present invention, it is possible to provide an electronic device with improved display characteristics.

  Hereinafter, an embodiment of an organic EL display device according to the present invention, a manufacturing method thereof, and an electronic device will be described with reference to the drawings. In the following drawings, the scale of each member and each layer is appropriately changed in order to facilitate the recognition of each member and each layer.

(First embodiment)
FIG. 1 is a schematic view of an active matrix type organic EL display device employing the organic EL display device according to the present invention. The illustrated organic EL display device 1 employs an active driving method using thin film transistors.

  The organic EL display device 1 includes a circuit element unit 14 including a thin film transistor as a circuit element on a substrate 2, a pixel electrode (anode) 111, an organic functional layer 110 including an organic EL layer (light emitting layer), and a counter electrode (cathode) 12. A plurality of organic EL elements 10 having a structure in which the sealing portions 3 and the like are sequentially stacked are arranged in a matrix.

  As the substrate 2, a glass substrate is used in the present embodiment. As the substrate 2, various known substrates used for electro-optical devices and circuit substrates such as a silicon substrate, a quartz substrate, a ceramic substrate, a plastic substrate, and a plastic film substrate can be used in addition to a glass substrate. The surface of the substrate 2 (the lower surface in FIG. 1) is preferably subjected to a dereflection treatment that suppresses reflection of external light. Since the reflection of external light can be suppressed by subjecting the surface of the substrate 2 to the antireflection treatment, the contrast of the organic EL display device 1 can be improved. In the substrate 2, a plurality of pixel areas A as arrangement areas of the organic functional layers are arranged in a matrix, and when performing color display, for example, red (R), green (G), blue (B) Pixel areas A corresponding to the respective colors are arranged in a predetermined arrangement. In each pixel region A, a pixel electrode 111 is arranged, and in the vicinity thereof, a signal line 132, a power supply line 133, a scanning line 131, scanning lines for other pixel electrodes (not shown), and the like are arranged. As the planar shape of the pixel region A, an arbitrary shape such as a circle or an oval is applied in addition to a rectangle as illustrated.

  The sealing portion 3 prevents oxidation of the cathode 12 or the organic functional layer 110 by preventing water and oxygen from entering. The sealing resin applied to the substrate 2 and the seal bonded to the substrate 2 are used. A stop substrate 3b (sealing can) and the like are included. As the material of the sealing resin, for example, a thermosetting resin or an ultraviolet curable resin is used, and in particular, an epoxy resin which is a kind of thermosetting resin is preferably used. The sealing resin is annularly applied to the periphery of the substrate 2 and is applied by, for example, a microdispenser. The sealing substrate 3b is made of glass, metal, or the like, and the substrate 2 and the sealing substrate 3b are bonded together via a sealing resin.

  FIG. 2 shows a circuit structure of the organic EL display device 1. In FIG. 2, on the support surface 2a of the substrate 2, a plurality of scanning lines 131, a plurality of signal lines 132 extending in a direction intersecting the scanning lines 131, and a plurality of power supply lines 133 extending in parallel with the signal lines. And are wired. Further, the pixel region A is formed at each intersection of the scanning line 131 and the signal line 132. For example, the data line driving circuit 103 including a shift register, a level shifter, a video line, and an analog switch is connected to the signal line 132. Further, the scanning line drive circuit 104 including a shift register and a level shifter is connected to the scanning line 131.

  In the pixel region A, a switching thin film transistor 123 in which a scanning signal is supplied to the gate electrode through the scanning line 131 and a storage capacitor for holding an image signal supplied from the signal line 132 through the switching thin film transistor 123. 135, a driving thin film transistor 124 to which an image signal held by the storage capacitor 135 is supplied to the gate electrode, and the power line 133 when electrically connected to the power line 133 through the driving thin film transistor 124 A pixel electrode (anode) 111 into which a driving current flows and an organic functional layer 110 sandwiched between the pixel electrode 111 and the cathode 12 are provided. The organic functional layer 110 includes a light emitting layer as an organic EL element.

  In the pixel region A, when the scanning line 131 is driven and the switching thin film transistor 123 is turned on, the potential of the signal line 132 at that time is held in the holding capacitor 135, and the driving thin film transistor according to the state of the holding capacitor 135. The conduction state of 124 is determined. In addition, a current flows from the power supply line 133 to the pixel electrode 111 through the channel of the driving thin film transistor 124, and further a current flows to the cathode 12 through the organic functional layer 110. The organic functional layer 110 emits light according to the amount of current at this time.

  FIG. 3 is an enlarged view of the cross-sectional structure of the display area in the organic EL display device 1. FIG. 3 shows a cross-sectional structure of three pixel regions corresponding to red (R), green (G), and blue (B) colors. As described above, the organic EL display device 1 includes the circuit element unit 14 in which a circuit such as a TFT is formed on the support surface 2 a of the substrate 2, and the light emitting element unit 11 in which the pixel electrode 111 and the organic functional layer 110 are formed. And the cathode 12 are sequentially laminated. In the organic EL display device 1, emitted light emitted from the organic functional layer 110 to the substrate 2 side is transmitted through the circuit element unit 14 and the substrate 2 and emitted to the lower side (viewing direction side) of the substrate 2, and the organic function. Light emitted from the layer 110 to the opposite side of the substrate 2 is reflected by the cathode 12, passes through the circuit element portion 14 and the substrate 2, and is emitted to the lower side (viewing direction side) of the substrate 2.

In the circuit element portion 14, a base protective film 2 c made of an SiO ₂ film is formed on the substrate 2, and an island-shaped semiconductor film 141 made of polycrystalline silicon is formed on the base protective layer 2 c. Note that a source region 141a and a drain region 141b are formed in the semiconductor film 141 by high concentration P ion implantation. A portion where P is not introduced is a channel region 141c. Further, a transparent gate insulating film 142 covering the base protective film 2c and the semiconductor film 141 is formed in the circuit element portion 14, and a gate electrode 143 made of Al, Mo, Ta, Ti, W, or the like is formed on the gate insulating film 142. (Scanning lines) are formed, and a transparent first interlayer insulating film 144 a and a second interlayer insulating film 144 b are formed on the gate electrode 143 and the gate insulating film 142. The gate electrode 143 is provided at a position corresponding to the channel region 141c of the semiconductor film 141. Also, contact holes 145 and 146 are formed through the first and second interlayer insulating films 144a and 144b and connected to the source and drain regions 141a and 141b of the semiconductor film 141, respectively.

  A transparent pixel electrode 111 made of ITO (Indium Tin Oxide) or the like is formed on the second interlayer insulating film 144b by patterning into a predetermined shape, and one contact hole 145 is connected to the pixel electrode 111. ing. In this manner, the driving switching thin film transistor 123 connected to each pixel electrode 111 is formed in the circuit element portion 14. The circuit element unit 14 is also formed with the storage capacitor 135 and the driving thin film transistor 124 described above, but these are not shown in FIG.

  The light emitting element unit 11 mainly includes an organic functional layer 110 stacked on each of the plurality of pixel electrodes 111 and a bank unit 112 disposed between the organic functional layers 110 to partition each organic functional layer 110. It is configured. A cathode 12 is disposed on the organic functional layer 110. The organic EL element 10 that is a light emitting element includes a pixel electrode 111, a cathode 12, an organic functional layer 110, and the like. Here, the pixel electrode 111 is made of ITO, and is formed by patterning into a substantially rectangular shape in plan view. The thickness of the pixel electrode 111 is preferably in the range of 40 to 150 nm.

As shown in FIG. 3, the bank portion 112 is formed by laminating an inorganic bank layer 112a (bank portion) located on the substrate 2 side and an organic bank layer 112b formed adjacent to the inorganic bank layer 112a. ing. Inorganic bank layer 112a, for example, an inorganic insulating material having a light-transmitting property with respect to the luminescent light such as SiO _2, openings 112a1 which the organic functional layer 110 is disposed inside is formed. As shown in the drawing, an opening 112b1 corresponding to the light emitting region b is formed in the organic bank layer 112b. In the present embodiment, the organic bank layer 112b does not transmit light with respect to emitted light.
And the organic functional layer 110 is arrange | positioned in the opening part 112a1 by arrange | positioning the organic functional layer 110 on the pixel electrode 111 exposed to the opening part 112a1 of this inorganic substance bank layer 112a.
In the organic EL display device 1 of the present embodiment, the upper surface 112c (scattering portion, reflecting portion) of the inorganic bank layer 112a exposed to the opening 112b1 of the organic bank layer 112b is roughened.

  The organic functional layer 110 includes a hole injection / transport layer 110a stacked on the pixel electrode 111, and a light emitting layer (organic EL layer) 110b formed adjacent to the hole injection / transport layer 110a. ing. The hole injection / transport layer 110a has a function of injecting holes into the light emitting layer 110b and a function of transporting holes inside the hole injection / transport layer 110a. By providing such a hole injecting / transporting layer 110a between the pixel electrode 111 and the light emitting layer 110a, device characteristics such as light emitting efficiency and life of the light emitting layer 110b are improved. Further, in the light emitting layer 110b, holes injected from the hole injection / transport layer 110a and electrons injected from the cathode 12 are recombined in the light emitting layer 110b, and light emission is obtained.

  The light emitting layer 110b includes three types of light emission wavelength bands different from each other in the red light emitting layer 110b1 emitting red (R), the green light emitting layer 110b2 emitting green (G), and the blue light emitting layer 110b3 emitting blue (B). Each of the light emitting layers 110b1 to 110b3 is arranged in a predetermined arrangement (for example, a stripe shape).

  Next, the cathode 12 is formed on the entire surface of the light emitting element portion 11, and plays a role of injecting electrons into the light emitting layer 110b. The cathode 12 is configured by laminating a calcium layer 12a and an aluminum layer 12b. The layer thickness of the calcium layer is preferably in the range of 2 to 50 nm, for example. The aluminum layer 12b reflects the light emitted from the light emitting layers 110b1 to 110b3 toward the substrate 2, and is preferably made of an Ag film, an Al / Ag laminated film, or the like in addition to the Al film. The thickness is preferably in the range of 100 to 1000 nm, for example. Note that the number of cathodes is not limited to 12, and any cathode can be used as long as it can efficiently inject electrons into the light emitting layer 110b.

  According to the organic EL display device 1 of the present embodiment configured as described above, as shown in FIG. 3, the emitted light L emitted sideways from the light emitting layer 110b and guided in the inorganic bank layer 112a is The light is scattered on the upper surface 112c of the inorganic bank layer 112a, and a part of the light L1 is reflected in the viewing direction. That is, conventionally emitted light that has been emitted laterally from the light emitting layer 110b, guided through the inorganic bank layer 112a, and eventually disappeared is reflected in the viewing direction, so that it is reflected in the organic EL display device 1 of the present embodiment. Accordingly, the emission efficiency of the emitted light can be improved as compared with the conventional organic EL display device.

In the organic EL display device 1 of this embodiment, as described above, the emitted light L guided in the inorganic bank layer 112a is scattered on the upper surface 112c of the inorganic bank layer 112a, and a part of the light L1 is emitted. Is reflected in the viewing direction, so that it appears as if the upper surface 112c of the inorganic bank layer 112a that scatters the emitted light L is emitted. Therefore, in the organic EL display device 1 of the present embodiment, the region partitioned by the organic bank layer 112b, that is, the region including the pixel region A that is the organic functional layer arrangement region and the upper surface 112c of the inorganic bank layer 112a emits light. Region b.
Accordingly, the organic EL display device 1 according to the present embodiment has improved emission efficiency of emitted light, and further has a wider area than the conventional one, which is superior to the conventional organic EL display device. Display characteristics can be obtained.
On the contrary, when the display characteristics equivalent to those of the conventional organic EL display device are sufficient, a wider area than the conventional area including the upper surface 112c of the inorganic bank layer 112a is set as the light emitting area. Compared with the EL display device, the current application area to the light emitting region can be reduced. For this reason, display characteristics equivalent to those of a conventional organic EL display device can be obtained with a small drive current, and an organic EL display device with excellent reliability can be realized.
As shown in FIG. 3, the organic EL display device 1 of the present embodiment employs a configuration in which the organic functional layer 110, that is, the pixel region A is disposed at the approximate center of the light emitting region b. According to the organic EL display device 1, since the upper surface 112c of the inorganic bank layer 112a can be used as the light emitting region b, it is possible to adopt a configuration in which the pixel region A is arranged away from the approximate center of the light emitting region b. .

  Further, as shown in FIG. 3, in the organic EL display device 1 of the present embodiment, the cathode 12 is formed on the entire surface of the light emitting element portion 11, and therefore is adjacent to the upper surface 112c of the inorganic bank layer 112a. For this reason, in the organic EL display device 1 of the present embodiment, the cathode 12 plays a role of injecting electrons into the light emitting layer 110b, and the emitted light L is scattered on the upper surface 112c of the inorganic bank layer 112a. It functions as a reflective film that reflects light reflected in the direction (cathode side direction) in the viewing direction. As described above, in the organic EL display device 1 of the present embodiment, since the cathode 12 is adjacent to the upper surface 112c of the inorganic bank layer 112a, part of the emitted light reflected upward is also emitted in the viewing direction. Therefore, the emission efficiency of emitted light can be further improved.

  In the organic EL display device 1 of the present embodiment, the surface roughness of the upper surface 112c of the inorganic bank layer 112a is preferably Ra = 10 to 100 nm. Thus, by setting the surface roughness of the upper surface 112c of the inorganic bank layer 112a to Ra = 10 to 100 nm, more emitted light can be scattered by the upper surface 112c of the inorganic bank layer 112a, and the emission efficiency of the emitted light can be further increased. Can be improved.

  Next, a method for manufacturing the organic EL display device 1 of the present embodiment will be described with reference to the drawings. The manufacturing method of the organic EL display device 1 of the present embodiment includes, for example, (1) an inorganic bank layer forming step, (2) a roughening step, (3) an organic bank layer forming step, and (4) lyophilic and lyophobic. A processing step, (5) a hole injection / transport layer forming step, (6) a light emitting layer forming step, (7) a cathode forming step, and (8) a sealing step. In addition, a manufacturing method is not restricted to this, When other processes are removed as needed, it may be added. The (5) hole injection / transport layer forming step and (6) light emitting layer forming step were performed using a droplet discharge method (inkjet method) using a droplet discharge device.

(1) Inorganic bank layer forming step The inorganic bank layer forming step is a step of forming the inorganic bank layer 112 a (bank portion) and the organic bank layer 112 a of the substrate 2 on the support surface 2 a of the substrate 2. The formation method will be described below.
First, as shown in FIG. 4A, a circuit element portion 14 such as a scanning line, a signal line, and a thin film transistor 123 is provided on a support surface 2a of a substrate 2, and a plurality of pixels are provided on interlayer insulating films 144a and 144b. An element substrate on which the electrode 111 is formed is prepared. Then, an inorganic bank layer 112a made of SiO ₂ having a flat upper surface 112c is formed on the substrate 2 by a liquid phase method using polysilazane as shown in FIG. 4B.

(2) Roughening process (reflection part forming process)
The roughening step is a step of roughening the upper surface 112c of the inorganic bank layer 112a. In the roughening step, as shown in FIG. 4C, the upper surface 112c of the inorganic bank layer 112a is roughened by performing CF ₄ plasma treatment on the upper surface 112c of the inorganic bank layer 112a. In this roughening step, it is preferable that the surface roughness of the upper surface 112c of the inorganic bank 112a is roughened so that Ra = 10 to 100 nm. Thus, by setting the surface roughness of the upper surface 112c of the inorganic bank 112a to Ra = 10 to 100 nm, the emitted light can be more efficiently scattered on the upper surface 112c (scattering portion) of the inorganic bank 112a. In addition, even if this roughening process is not performed, in the above-mentioned inorganic bank layer formation process, when the upper surface 112c of the inorganic bank layer 112a is roughened, even if this roughening process is not performed. good.

(3) Organic Bank Layer Forming Step The organic bank layer forming step is a step of forming an organic bank layer 112b for partitioning the light emitting region b between the light emitting regions b. First, before performing the organic bank layer forming step, the inorganic bank layer 112a is etched to form an opening 112a1 in which the organic functional layer 110 is disposed and an opening 112a2 located between the light emitting regions b. To do. Note that the pixel region A, which is an organic functional layer arrangement region, is formed by the opening 112a1.
Thereafter, an organic bank layer forming step is performed. Specifically, an organic bank material is arranged with a predetermined thickness by, for example, a spin coating method, and the arranged organic bank material is pre-baked, and then known photolithography is performed. By patterning the organic bank material using the method and further performing the main baking, the organic bank layer 112b disposed on the opening 112a2 of the inorganic bank 112a as shown in FIG. 4D is formed.
In addition, the bank part formation process of this invention has the inorganic substance bank layer formation process and the organic substance bank layer formation process in this embodiment, and is comprised.

(4) Lipophilic and lyophobic treatment process The lyophilic process is performed for the purpose of activating the surface of the pixel electrode 111 exposed in the opening 112a1 of the inorganic bank 112a.
As the lyophilic treatment step, an ultraviolet (UV) irradiation treatment for lyophilicizing the surface of the pixel electrode 111 by irradiating ultraviolet rays, an O ₂ plasma treatment using oxygen as a treatment gas in an atmospheric atmosphere, or the like can be selected. Then, O ₂ plasma treatment is performed.
Specifically, the residue on the pixel electrode 111 is treated by irradiating the surface of the pixel electrode 111 with plasma oxygen from the plasma discharge electrode, thereby imparting lyophilicity to the pixel electrode 111. .
Further, the surface of the organic bank 112b is selectively subjected to water repellency by performing CF ₄ plasma treatment on the substrate surface.

(5) Hole Injection / Transport Layer Formation Step Subsequently, the hole injection / transport layer 110a is formed on the substrate 2 on which the pixel electrode 111 is formed. In the hole injection / transport layer forming step, here, a polar solvent containing a hole injection / transport layer forming material is discharged onto the pixel electrode 111 as the composition ink B by using a droplet discharge method. Thereafter, a drying process and a heat treatment are performed to form the hole injection / transport layer 110 a on the pixel electrode 111. The subsequent steps including the hole injection / transport layer forming step are preferably performed in an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere.

As a procedure for forming the hole injection / transport layer 110a by the droplet discharge method, a discharge head (not shown) for discharging droplets is filled with a composition ink containing the material of the hole injection / transport layer 110a. The amount of liquid per droplet was controlled from the discharge nozzle while the discharge nozzle of the discharge head was opposed to the pixel electrode 111 positioned in the opening of the bank unit 112 and the discharge head and the substrate 2 were relatively moved. Ink droplets are ejected and placed on the pixel electrode 111.
Thereafter, the ejected ink droplets are dried to evaporate the polar solvent contained in the composition ink, so that the hole injection / transport layer 110a having a desired film thickness becomes an inorganic substance as shown in FIG. It is formed in the opening 112a1 of the bank layer 112a.

  As the composition used here, for example, a composition obtained by dissolving a mixture of a polythiophene derivative such as polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid (PSS) in a polar solvent can be used. Examples of the polar solvent include isopropyl alcohol (IPA), normal butanol, γ-butyrolactone, N-methylpyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI) and its derivatives, carbitol acetate And glycol ethers such as butyl carbitol acetate. More specifically, the composition of the PEDOT: PSS mixture (PEDOT / PSS = 1: 20): 12.52 wt%, PSS: 1.44 wt%, IPA: 10 wt%, NMP: 27.48 A weight%, DMI: 50 weight% can be illustrated. The viscosity of the composition is preferably about 2 to 20 Ps, particularly about 4 to 15 cPs.

(6) Light-Emitting Layer Formation Step Next, the light-emitting layer 110b is formed on the pixel electrode 111 on which the hole injection / transport layer 110a is stacked. Here, a composition ink containing a light emitting layer material is discharged onto the hole injection / transport layer 110a by a droplet discharge method, and then dried and heat-treated, and each color is formed in the opening formed in the bank portion 112. The light emitting layers 110b1 to 110b3 are formed.

  In the light emitting layer forming step, non-polarity that is insoluble in the hole injecting / transporting layer 110a is used as a solvent for the composition ink used in forming the light emitting layer in order to prevent re-dissolution of the hole injecting / transporting layer 110a. Use solvent. In this case, in order to improve the wettability of the surface of the hole injection / transport layer 110a with respect to the nonpolar solvent, it is preferable to perform a surface modification step before forming the light emitting layer. The surface modification step is performed, for example, by applying the same solvent as the nonpolar solvent or a similar solvent on the hole injection / transport layer 110a by a droplet discharge method, a spin coating method, a dip method, or the like and then drying. . Examples of the surface modifying solvent used here are cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, tetramethylbenzene and the like as the nonpolar solvent of the composition ink. Examples of the solvent are toluene, xylene and the like.

  As a procedure for forming a light emitting layer by the droplet discharge method, first, when forming a blue light emitting layer, a nonpolar solvent containing a material for forming the blue light emitting layer 110b3 is filled in the discharge head (not shown) as a composition ink. The discharge head of the discharge head is opposed to the blue (B) hole injection / transport layer 110a located in the opening 112b1 of the organic bank layer 112b, and the discharge head and the substrate 2 are moved relative to each other. Ink droplets having a controlled amount of liquid per droplet are ejected from the nozzle. The ejected ink droplet spreads on the hole injection / transport layer 110a and fills the opening 112a1 of the inorganic bank layer 112a. Subsequently, the non-polar solvent contained in the composition ink is evaporated by drying the ejected ink droplets, and a blue light emitting layer 110b3 having a desired film thickness is formed as shown in FIG. 5 (f). .

  As a light emitting material for forming the blue light emitting layer 110b3, for example, a material made of an organic EL material such as polydialkylfluorene and a derivative thereof, distyrylbiphenyl and a derivative thereof, tetraphenylbutadiene and a derivative thereof can be used. On the other hand, as the nonpolar solvent, those insoluble in the hole injection / transport layer are preferable. For example, cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, tetramethylbenzene, and the like can be used.

Subsequently, as shown in FIG. 5G, the red light emitting layer 110b1 and the green light emitting layer are formed on the red (R) and green (G) pixel electrodes 111 on which the hole injection / transport layer 110a is disposed. 110b2 is formed. The red and green light emitting layer forming steps are performed in the same procedure as the blue light emitting layer forming step described above. That is, a composition ink containing a material for forming the green light emitting layer 110b2 is ejected onto the green (G) hole injecting / transporting layer 110a by a droplet ejection method, and then dried and heat-treated to form an organic bank layer. A green light emitting layer 110b2 having a desired thickness is formed in the opening 112b1 formed in 112b. In addition, a composition ink containing a material for forming the red light-emitting layer 110b1 is discharged onto the red (R) hole injection / transport layer 110a by a droplet discharge method, and then dried and heat-treated to thereby form an organic bank layer. A red light emitting layer 110b1 having a desired thickness is formed in the opening 112b1 formed in 112b. In addition, as a luminescent material which forms green light emitting layer 110b2, what consists of organic EL materials, such as polyparaphenylene vinylene and its derivative (s), polyfluorene derivative F8BT, can be used, for example, and the luminescent material which forms red light emitting layer 110b1 For example, a material obtained by adding a pigment such as rhodamine to polyparaphenylene vinylene or a material made of an organic EL material such as a polyfluorene derivative can be used.
In addition, the organic functional layer formation process of this invention has a positive hole injection / transport layer formation process and a light emitting layer formation process in this embodiment, and is comprised.

(7) Cathode Formation Step Next, as shown in FIG. 5H, a counter electrode (cathode) 12 that forms a pair with the pixel electrode (anode) 111 is formed. That is, the cathode 12 is formed by sequentially laminating the calcium layer 12a and the aluminum layer 12b on the entire surface of the substrate 2 including each color light emitting layer 110b and the organic bank layer 112b. Thereby, the cathode 12 is laminated | stacked on the whole formation area of each color light emitting layer 110b, and the organic EL element corresponding to each color of red (R), green (G), and blue (B) is formed, respectively. The cathode 12 is preferably formed by, for example, a vapor deposition method, a sputtering method, a CVD method, or the like, and particularly preferably formed by a vapor deposition method in terms of preventing damage to the light emitting layer 110b due to heat or an electron beam. Further, a protective layer such as SiO ₂ or SiN may be provided on the cathode 12 to prevent oxidation. In addition to Ca, metals having a work function of 3.5 eV or less, such as Mg, Sr, Ba, Li, Na, K, Yb, and Sm can be used. Further, before depositing these metals, a metal oxide, fluoride, metal complex, or the like such as LiF or Li 2 O may be formed as an electron injection layer or a hole blocking layer. In addition to Al, a highly reflective metal such as silver can be used as the auxiliary cathode.

  Since such a cathode 12 includes the aluminum layer 12b, it has a function of reflecting emitted light. Since the cathode 12 is formed on the entire surface of the substrate 2, it is also formed on the upper surface 112c of the inorganic bank 112a. For this reason, in the organic EL display device 1 of the present embodiment, the cathode 12 can be used as the reflective film of the present invention. Moreover, in the manufacturing method of the organic EL display device of this embodiment, the reflective film of the present invention can be formed simultaneously with the formation of the cathode 12.

(8) Sealing process Finally, the board | substrate 2 in which the display element part 10 was formed, and the sealing can 3b are sealed via sealing resin. For example, a sealing resin made of a thermosetting resin or an ultraviolet curable resin is applied to the peripheral portion of the substrate 2, and the sealing can 3b is disposed on the sealing resin. The sealing step is preferably performed in an inert gas atmosphere such as nitrogen, argon, or helium. If it is carried out in the air, when a defect such as a pinhole has occurred in the cathode 12, water or oxygen may enter the cathode 12 from the defective portion and the cathode 12 may be oxidized, which is not preferable. Of course, instead of the sealing can, a glass substrate may be bonded over the entire surface with the above-mentioned effect resin. Or you may seal with a thin film with high gas-barrier property. In this case, the gas barrier property is improved by forming a multilayer structure.

  Thereafter, the cathode 12 is connected to the wiring of the substrate 2, and the wiring of the circuit element unit 14 is connected to a driving IC (driving circuit) provided on or outside the substrate 2, whereby the organic EL display device of the present embodiment. 1 is completed.

(Example)
An organic EL display device according to the first embodiment in which an inorganic bank layer made of SiO ₂ is formed, and the upper surface of the inorganic bank layer is roughened with CF ₄ plasma so that the surface roughness Ra = 50 nm is provided. When actually manufactured, the emission efficiency was confirmed to be 1.5 times that of the conventional organic EL display device.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In the description of the second embodiment, the description of the same parts as in the first embodiment will be omitted or simplified.

  FIG. 6 is an enlarged view of the cross-sectional structure of the display region in the organic EL display device 4 of the second embodiment. The organic EL display device 4 of the second embodiment shown in this figure has an organic bank layer 112d (base portion) made of an organic substance instead of the inorganic bank layer 112a provided in the organic EL display device 1 of the first embodiment. Is provided. Unlike the organic bank layer 112b formed between the light emitting regions b, the organic bank layer 112d is formed of a material that is transparent to the emitted light L. In the organic EL display device 4 of the second embodiment, the upper surface 112e of the organic bank layer 112d is roughened.

  Also in the organic EL display device 4 of the second embodiment having such a configuration, the emitted light L emitted from the light emitting layer 110b and guided through the organic bank layer 112d is scattered on the upper surface 112e of the organic bank layer 112d. , A part of the light L1 is reflected in the viewing direction. For this reason, also in the organic EL display device of the second embodiment, the emission efficiency can be improved as compared with the conventional organic EL display device.

  When the emitted light L emitted laterally from the light emitting layer 110b is reflected at the interface between the light emitting layer 110b and the organic bank layer 112d, the reflected emitted light L is confined in the light emitting layer 110b. , Will eventually disappear. For this reason, reducing the reflectance at the interface between the light emitting layer 110b and the organic bank layer 112d is a factor in improving the emission efficiency of the organic EL display device. Therefore, in the organic EL display device 4 of the second embodiment, it is preferable to form the light emitting layer 110b and the organic bank layer 112d with materials having substantially the same refractive index. Since the current refractive index of the light emitting layer 110b is about 1.7, it is preferable to employ the organic bank layer 112d whose main skeleton is made of a bisphenol-based material in the organic EL display device 4 of the second embodiment. . Accordingly, the refractive index of the light emitting layer 110b and the refractive index of the organic bank layer 112d can be made substantially the same, and the reflectance at the interface between the light emitting layer 110b and the organic bank layer 112d can be reduced. Accordingly, the amount of the emitted light L guided in the organic bank layer 112d is increased, and the emission efficiency of the organic EL display device 4 can be further improved. When the refractive index of the light emitting layer 110b is changed from 1.7, it is preferable to form the organic bank layer 112d made of a material suitable for the refractive index.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. In the description of the third embodiment, the description of the same parts as those of the second embodiment will be omitted or simplified.

  FIG. 7 is an enlarged view of the cross-sectional structure of the display region in the organic EL display device 5 of the third embodiment. In the organic EL display device 4 of the third embodiment shown in this figure, the upper surface 112e of the organic bank layer 112d is set to the reflective surface shape of the light guide plate. In this way, by making the upper surface 112e of the organic bank layer 112d into the shape of the reflecting surface of the light guide plate, more emitted light L can be reflected in the viewing direction. For this reason, according to the organic EL display device 5 of the third embodiment, the emission efficiency can be further improved.

  When forming the organic bank layer 112d of the organic EL display device 5 of the third embodiment having such a configuration, a photocurable resin material is applied on the substrate as shown in FIG. The mold K in which the reflection surface shape of the light guide plate is formed on the pressing surface K1 is pressed against the resin material. Thereafter, the resin material is cured by light irradiation, the mold K is removed, and then patterning is performed, whereby the organic bank layer 112d having the upper surface 112e that is the reflective surface shape of the light guide plate can be formed. And by performing such a process, the organic electroluminescence display 5 provided with the organic substance bank layer 112d by which the upper surface 112e was made into the reflective surface shape of a light-guide plate can be manufactured.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. Note that in the fourth embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

  FIG. 9 is an enlarged view of the cross-sectional structure of the display area in the organic EL display device 6 of the fourth embodiment. As shown in this figure, in the organic EL display device 6 of the fourth embodiment, a reflective film 112g is formed on the side surface 112f on the non-light emitting layer side of the inorganic bank layer 112a that is set in a reverse taper shape.

  According to the organic EL display device 6 of the fourth embodiment having such a configuration, the emitted light L emitted laterally from the light emitting layer 110b and guided in the inorganic bank layer 112a is viewed in the viewing direction by the reflective film 112g. Is reflected. For this reason, according to the organic EL display device 6 of the fourth embodiment, the emission efficiency can be further improved, and the light emitting region b can be further expanded. In the organic EL display devices 4 and 5 shown in the second and third embodiments, the reflective film 112g is formed on the side surface on the non-light emitting layer side of the organic bank layer 112d having a reverse tapered shape. The emission efficiency can be improved and the light emitting region b can be widened.

(Fifth embodiment)
Next, a fifth embodiment of the organic EL display device will be described. In the first embodiment, light emitted from the organic functional layer 110 is emitted to the lower side (observer side) of the substrate 2, whereas in the present embodiment, the upper side of the sealing substrate 3 b. (Observer side) is released. The difference between the present embodiment and the first embodiment is mainly the material configuration, and in this embodiment, the parts different from the first embodiment will be described. Therefore, the description of the fifth embodiment will be described with reference to FIGS.

  In the present embodiment, light emission is extracted from the side of the sealing substrate 3 b that is the opposite side of the substrate 2, so that either a transparent substrate or an opaque substrate can be used as the substrate 2. Examples of the opaque substrate include a thermosetting resin and a thermoplastic resin in addition to a ceramic sheet such as alumina and a metal sheet such as stainless steel that has been subjected to an insulation treatment such as surface oxidation.

  In addition, the pixel electrode 111 is not necessarily limited to a transparent material, and a suitable material satisfying the function of the anode is used, and a material having light reflectivity is preferable, and Al or the like is employed. In addition, when adopting transparent metal ITO etc. as the pixel electrode 111, the structure which forms Al thin film etc. in the lower layer, and has light reflectivity is preferable.

  Moreover, as a material of the cathode 12, it needs to have transparency and transparent metals, such as ITO, are employ | adopted. Further, as the material of the sealing substrate 3b, a suitable material having transparency is adopted. In addition, it is preferable that the surface of the sealing substrate 3b is subjected to a dereflection treatment similarly to the surface of the substrate 2 of the first embodiment described above.

  In the organic EL display device configured as described above, it is possible to emit light emitted from the organic functional layer 110 from the sealing substrate 3b side.

  Also in the organic EL display device of the fifth embodiment having such a configuration, the emitted light L guided in the inorganic bank layer 112a is scattered on the upper surface 112c of the inorganic bank layer 112a, and a part thereof is upward ( (Viewing direction). For this reason, also in the organic EL display device of the fifth embodiment, the emission efficiency can be improved and the display area b can be expanded as compared with the conventional organic EL display device.

  In the present embodiment, the first embodiment and the modified example have been described. However, the second and third embodiments also adopt a configuration in which light emission is extracted from the sealing substrate 3b side that is the opposite side of the substrate 2. can do.

<Electronic equipment>
10A to 10C show an embodiment of an electronic apparatus according to the present invention. The electronic apparatus of this example includes the organic EL display device of the present invention such as the above-described electroluminescence device as a display unit.
FIG. 10A is a perspective view showing an example of a mobile phone. In FIG. 10A, reference numeral 1000 denotes a mobile phone body, and reference numeral 1001 denotes a display unit using the above display device.
FIG. 10B is a perspective view illustrating an example of a wristwatch type electronic device. In FIG. 10B, reference numeral 1100 denotes a watch body, and reference numeral 1101 denotes a display unit using the above display device.
FIG. 10C is a perspective view showing an example of a portable information processing apparatus such as a word processor or a personal computer. In FIG. 10C, reference numeral 1200 denotes an information processing apparatus, reference numeral 1202 denotes an input unit such as a keyboard, reference numeral 1204 denotes an information processing apparatus body, and reference numeral 1206 denotes a display unit using the above display device.
Since each of the electronic devices shown in FIGS. 10A to 10C includes the organic EL display device of the present invention in the display portion, good light emission characteristics can be obtained.

  In addition to the above-described examples, other examples include a liquid crystal television, a viewfinder type and a monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a video phone, a POS terminal, electronic paper, and a touch panel. And the like. The electro-optical device of the present invention can also be applied as a display unit of such an electronic apparatus.

  The preferred embodiments of the organic EL display device, the manufacturing method thereof, and the electronic apparatus according to the present invention have been described above with reference to the accompanying drawings. Needless to say, the present invention is not limited to the above-described embodiments. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the first embodiment, the inorganic bank layer 112a is formed using the liquid phase method. However, the present invention is not limited to this, and for example, the inorganic bank layer 112a can be formed using a vapor deposition method. In such a case, due to the characteristics of the vapor deposition method, unevenness corresponding to the base is formed on the upper surface 112c of the inorganic bank layer 112a. Even in such a case, the upper surface 112c of the inorganic bank layer 112a is not formed. By roughening the surface, the emitted light L guided through the inorganic bank layer 112a can be scattered.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows typically the structure of the organic electroluminescence display of 1st Embodiment of this invention. The circuit diagram which shows the circuit of an active matrix type organic electroluminescence display. The enlarged view which shows the cross-section of the display area of the organic electroluminescence display of 1st Embodiment. Explanatory drawing for demonstrating the manufacturing method of the organic electroluminescence display of 1st Embodiment. Explanatory drawing for demonstrating the manufacturing method of the organic electroluminescence display of 1st Embodiment. Sectional drawing which shows the cross-section of the display area of the organic electroluminescence display of 2nd Embodiment of this invention. Sectional drawing which shows the cross-section of the display area | region of the organic electroluminescence display of 3rd Embodiment of this invention. Explanatory drawing for demonstrating the manufacturing method of the organic electroluminescence display of 3rd Embodiment. Sectional drawing which shows the cross-section of the display area of the organic electroluminescence display of 4th Embodiment of this invention. FIG. 14 is a perspective view showing an embodiment of an electronic apparatus according to the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 4, 5 ... Organic EL display device, 2 ... Substrate, 110 ... Organic functional layer, 110b ... Light emitting layer, 112a ... Inorganic bank layer (bank part), 112c, 112e ... Upper surface (scattering part) , Reflective portion), 112d .... organic bank layer (bank portion), A .... pixel region (predetermined region), L..emission light, b..emission region

Claims (11)

An organic EL display device having an organic functional layer including at least a light emitting layer in a plurality of predetermined regions of a substrate, and performing display by emitting light emitted from the light emitting layer in a predetermined viewing direction,
A bank portion having the organic functional layer in an opening formed corresponding to the predetermined region and having translucency with respect to the emitted light;
An organic EL display device comprising: a reflecting portion that reflects all or part of the emitted light guided in the bank portion in the viewing direction. The organic EL display device according to claim 1, wherein the reflection unit is a scattering unit that scatters the emitted light. 3. The organic EL display device according to claim 2, wherein the scattering portion is a roughened upper surface of the bank portion. The organic EL display device according to claim 3, wherein the top surface of the bank portion has a surface roughness Ra = 10 to 100 nm. 3. The organic EL display device according to claim 2, wherein the scattering portion is an upper surface of the bank portion having a reflecting surface shape of a light guide plate. 6. The organic EL display device according to claim 3, further comprising a reflective film adjacent to an upper surface of the bank portion. A method of manufacturing an organic EL display device having an organic functional layer including at least a light emitting layer in a plurality of predetermined regions of a substrate and performing display by emitting light emitted from the light emitting layer in a predetermined viewing direction. And
A bank portion forming step for forming a bank portion having an opening formed corresponding to the predetermined region;
An organic functional layer forming step of forming the organic functional layer in the opening;
And a reflecting portion forming step of forming a reflecting portion that reflects all or part of the emitted light guided in the bank portion in the viewing direction. The method of manufacturing an organic EL display device according to claim 7, wherein the reflecting portion forming step includes a step of performing a plasma treatment on an upper surface of the bank portion. 8. The method of manufacturing an organic EL display device according to claim 7, wherein the reflecting portion forming step includes a step of performing a wet etching process on an upper surface of the bank portion. The said reflecting part formation process includes the process of shape | molding the upper surface of the said bank part in the reflective surface shape of a light-guide plate by pressing a predetermined type | mold with respect to the upper surface of the said bank part. Manufacturing method of organic EL display device. An electronic apparatus comprising the organic EL display device according to claim 1 as a display unit.

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