JP3999606B2 - Organic EL display device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device in which a light emitting element is provided between a pair of electrode elements, and an electric field is applied to the light emitting element by the pair of electrode elements to emit light , and a manufacturing method thereof .
[0002]
[Prior art]
In recent years, EL display devices using electroluminescence have been actively developed. The EL display device has a configuration in which a light emitting layer is provided between an anode and a cathode. In the EL display device, as in the liquid crystal display device, a passive drive method represented by a line-sequential method may be adopted in addition to an active drive method in which each pixel is individually driven by providing a switch such as a TFT for each pixel. it can. Such an EL display device can be classified into an inorganic EL display device and an organic EL display device depending on the type of the luminescent compound used.
[0003]
Here, as an example of the organic EL display device, as schematically shown in the cross section of the pixel in FIG. 7, the transparent electrode 53 as the anode, the hole transport layer 62, on the glass substrate first surface 52 a, Some have a structure in which a light emitting layer 63, an electron transport layer 64, and a reflective electrode 54 as a cathode are laminated in this order. In such an organic EL display device X ′, light generated in the light emitting layer 63 passes through the hole transport layer 62, the transparent electrode 53, and the glass substrate 52, and is emitted to the outside from the glass substrate second surface 52b. The light emission direction is defined as a first direction. In addition, some of the light generated in the light emitting layer 63 travels in the direction opposite to the first direction. Such backward light is reflected by the reflective electrode 54, and the organic layer 60, the transparent electrode 53, and the like. By passing through the glass substrate 52, the light is emitted to the outside in the first direction. Therefore, in the structure in which the transparent electrode 53, the organic layer 60, and the reflective electrode 54 are stacked on the glass substrate first surface 52a, all the light generated from the light emitting layer 63 in the organic layer 60 finally passes through the glass substrate 52. Therefore, only one surface of the glass substrate second surface 52b is used as a display screen.
[0004]
[Problems to be solved by the invention]
As described above, in the organic EL display device X ′ shown in FIG. 7, the display screen is basically only one surface of the glass substrate second surface 52b. For example, if both the transparent electrode 53 and the reflective electrode 54 are made of a transparent material, light can be emitted to the outside from the two surfaces of the glass substrate second surface 52b and the cathode first surface 54a. When a transparent material such as ITO is used for both the material 53 and the reflective electrode 54, the drive voltage is higher because the resistivity is higher than when the reflective electrode 54 is formed using a metal having a low resistivity such as copper or aluminum. Becomes larger. In addition, when light is emitted, since the light passes through the transparent electrode 53 and the glass substrate 52, the light amount of the light finally emitted from the glass substrate 52 is larger than the light amount emitted from the light emitting layer 63. Is less. Furthermore, when general ITO is used as the transparent electrode 53, the ITO has a wavelength selectivity that allows easy transmission of the long wavelength side of visible light. For example, the emitted light (display screen) becomes reddish. May have an effect.
[0005]
The present invention has been conceived under such circumstances, has a structure capable of emitting light in two directions with a relatively low driving voltage, and the amount of emitted light. An object of the present invention is to provide an organic EL display device capable of suppressing reduction and stabilizing color and a manufacturing method thereof.
[0006]
DISCLOSURE OF THE INVENTION
In order to solve the above problems, the present invention takes the following technical means.
[0007]
That is, the organic EL display device provided by the first aspect of the present invention includes a plurality of display elements provided on a substrate, and each of these display elements provides a first electrode element and an electric field. An organic EL display device having a configuration in which an organic element having a light emitting element that emits light and a second electrode element are stacked in this order, and a plurality of the first electrode elements are arranged in a row in a first direction A plurality of first electrodes arranged in a strip shape extending in the first direction and arranged in parallel in a second direction orthogonal to the first direction, and a plurality of the second electrode elements are A plurality of second electrodes arranged in a row aligned in the second direction and formed in a strip shape extending in the second direction and arranged in parallel in the first direction, and On each second electrode Each portion intersecting the plurality of first electrode, the opening of each one rectangular window hole shape is formed, while the light generated in the light emitting element is allowed to exit from the respective openings, the organic At least a part of the element is covered with a light-transmitting metal conductor layer, and the metal conductor layer is at least partially in contact with the second electrode element .
[0008]
In a preferred embodiment, the substrate and the first electrode element are formed to have translucency.
[0009]
The organic EL display device according to the present invention has a configuration in which a first electrode element, a light emitting element, and a second electrode element are stacked in this order on a substrate. Here, when the stacking direction is the stacking direction and the direction opposite to the stacking direction is the stacking reverse direction, the light generated in the light emitting element is stacked in the stacking direction from the opening provided in the second electrode element. It is possible to extract light in two directions, one that is emitted in the opposite direction and one that is transmitted through the transparent substrate and the first electrode element and emitted in the opposite direction of the stacking. In other words, even when light is extracted in two directions, both electrode elements do not need to be made of a transparent material. For example, if the second electrode element provided with the opening is made of a metal having a relatively low resistivity, it is low. Even with the driving voltage, light can be emitted in two directions without unevenness. Moreover, according to the said structure, passive drive is attained.
[0010]
By providing an opening in the second electrode element, even if both the first and second electrode elements are made of an opaque metal, light generated by the light emitting element can be extracted from the opening in the stacking direction. It is. Therefore, if both electrode elements are made of a material having a relatively low resistivity, light can be emitted evenly even at a low driving voltage. In addition, copper, aluminum, etc. are mentioned as a material with relatively low resistivity.
[0011]
In addition, since the emission of light in the stacking direction is performed from the opening, it is possible to suppress a decrease in the amount of light finally emitted to the outside as compared with the case where the light is transmitted through the electrode element and the substrate. Problems such as reddish emission light that may occur when passing through ITO do not occur, and instability of color is also eliminated.
[0013]
In addition, by forming the translucent metal conductor layer as described above, it is possible to compensate for the decrease in the contact area between the organic element and the second electrode element due to the provision of the opening in the configuration of the present invention. Thereby, the injection efficiency of electrons or holes can be improved. In addition, the resistance of the second electrode element itself, which has become larger due to the provision of the opening, can be reduced, whereby the drive voltage can be reduced. In order to suppress a decrease in the amount of light emitted from the opening in the stacking direction due to the formation of the metal conductor layer, the metal conductor layer is formed, for example, of gold or aluminum so as to have a thickness of 50 nm or less. ing.
[0014]
The opening is, for example, rectangular or substantially rectangular, and the dimension in the second direction at the opening is smaller than the dimension in the second direction at the first electrode.
[0015]
The manufacturing method of the organic EL display device provided by the second aspect of the present invention includes a plurality of display elements provided on a substrate, and each of these display elements provides a first electrode element and an electric field. The organic element having the light emitting element that emits light and the second electrode element are stacked in this order, and the plurality of the first electrode elements are arranged in a row aligned in the first direction and the above A plurality of first electrodes formed in a strip shape extending in the first direction and arranged in parallel in a second direction orthogonal to the first direction, and a plurality of the second electrode elements in the second direction A plurality of second electrodes arranged in a row and extending in the second direction and arranged in parallel in the first direction, and each of the second electrodes Intersects the plurality of first electrodes Each part, a method of manufacturing an organic EL display device in which the opening of the one rectangular window hole shape is formed, a plurality of second electrodes which the opening is formed, these second It forms by the 1st process of forming the strip-shaped part of the width direction both sides of an electrode, and the 2nd process of forming the part which connects the said strip-shaped part so that each said opening part may be pinched | interposed.
[0016]
Other advantages and features of the present invention will become more apparent from the following description of embodiments of the invention.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.
[0018]
An organic EL display device X according to a first embodiment of the present invention will be described with reference to FIGS.
[0019]
An organic EL display device X shown in FIG. 1 includes a substrate 2 and a cover 7, a plurality of anodes 3 and a plurality of cathodes 4 arranged on the substrate 2, a plurality of display elements 1 arranged in a matrix, It has. As shown in FIG. 2, the display element 1 includes a pair of electrode elements 33 and 34 (anode element 33 and cathode element 34) and an organic element 40 provided between the pair of electrode elements 33 and 34. The organic element 40 is configured to emit light by electroluminescence based on voltage application using the pair of electrode elements 33 and 34. The organic element 40 is a portion corresponding to each display element 1 in each organic layer 10.
[0020]
In addition, the display element 1 is configured to drive each display element 1 by passive driving by a line sequential method in the present embodiment, and is formed so that the anode element 33 and the cathode element 34 intersect each other. ing. The anode element 33 and the cathode element 34 are portions corresponding to the display elements 1 in the anodes 3 and the cathodes 4, respectively.
[0021]
Although not clearly shown on the drawing, the substrate 2 has, for example, a rectangular shape and is made of transparent glass or plastic film. Further, the substrate 2 has a substrate first surface 2a on which the display element 1 is formed, and a substrate second surface 2b that becomes one of light emission surfaces when the anode 3 and the substrate 2 are formed of a transparent material. ing. Hereinafter, the direction of light emitted through the substrate second surface 2b is defined as a first direction, and the direction of light emitted in the opposite direction is defined as a second direction.
[0022]
The anode 3 is formed in a strip shape in which a plurality of anode elements 33 are arranged in a row and extends in the direction of arrow AB in FIG. A plurality of anodes 3 are arranged in the width direction thereof. These anodes 3 are formed, for example, by performing vapor deposition, sputtering, etching, or the like after photolithography. In addition, as a material which forms the anode 3, ITO etc. are mentioned. In addition, when light is emitted only in one direction (second direction), the anode 3 may be opaque. Therefore, a material having high reflectivity and high hole injection efficiency into the organic layer 10 is selected. The
[0023]
The organic layer 10 is laminated on the anode 3, and as shown in FIGS. 1 and 2, the hole injection layer 11 provided to improve the hole injection efficiency from the anode 3, and the hole And a hole transport layer 12 having a function of preventing the exciton from contacting the hole injection layer 11 and serving as an electron barrier, and a luminescent substance. Are provided for improving the efficiency of electron injection from the cathode 4, the electron transport layer 14 having a function as a hole barrier, and transporting electrons to the light emitting layer 13. The injection layer 15 is included.
[0024]
Insulating partition walls 5 are provided between adjacent anodes 3 and between adjacent organic layers 10. The insulating partition 5 ensures electrical insulation between the anodes 3 and between the organic layers 10.
[0025]
The cathode 4 is formed in a strip shape in which a plurality of cathode elements 34 are arranged in a row and extends in the direction of the arrow CD in FIG. In addition, each cathode element 34 is configured to have a rectangular opening 9 serving as a light emission port in the second direction. Moreover, the some cathode 4 is located in a line with the arrow AB of FIG. The shape of the opening 9 is not limited to a rectangular shape, and may be a substantially rectangular shape, for example.
[0026]
These cathodes 4 are stacked on the organic layer 10 and the insulating partition 5. For example, as shown in FIG. 3, the anode 3, the insulating partition 5 and the organic layer 10 are stacked on the first surface 2 a of the substrate. A completed substrate 2A is formed through a cathode formation pre-process (illustrated in FIG. 4) and a cathode formation post-process (illustrated in FIG. 5). The material for forming the cathode 4 may be opaque because it has the opening 9, and in order to improve the electron injection into the organic layer 10, the work function or the electron affinity is higher. A small material is selected, and examples thereof include aluminum, a magnesium-silver alloy, and an aluminum-lithium alloy.
[0027]
The cathode formation pre-process is performed by, for example, a mask method. The metal mask 70 shown in FIG. 4 is placed on the layered substrate 2A shown in FIG. 3 by aligning the mask opening 71 with the portion where the metal is to be adhered, and then vacuum-deposited, and finally. A cathode 4a as shown in the lower diagram of FIG. 4 is formed.
[0028]
The post-cathode formation step is performed, for example, by a mask method. The metal mask 72 shown in FIG. 5 is placed on the substrate 2B on which the cathode 4a is formed shown in FIG. Then, the cathode 4 as shown in the lower diagram of FIG. 5 is formed. The opening 9 formed simultaneously with the formation of the cathode 4 is provided at a portion where the anode 3 and the cathode 4 intersect and has a rectangular shape or a substantially rectangular shape. Further, the dimension of the opening 9 in the arrow CD direction is formed to be smaller than the dimension of the anode 3 in the arrow CD direction. With this structure, light can be emitted uniformly from the entire surface of the opening 9.
[0029]
The cover 7 has a low refractive index deposited film layer 6 having an antireflection effect on the cover inner surface 7a, and is formed so as to cover and seal the substrate 2 of the organic EL display device X as shown in FIG. Is done. The cover 7 is fixed using an adhesive 30. In addition, as a material which comprises the cover 7, glass etc. are mentioned, As a material which comprises the low refractive index vapor deposition film layer 6, what is called AR coating etc. are mentioned.
[0030]
In the organic element 40, a hole injection element 41, a hole transport element 42, an organic element 43, an electron transport element 44, and an electron injection element 45 are laminated on the anode element 33 in this order. Note that the hole injection element 41, the hole transport element 42, the organic element 43, the electron transport element 44, and the electron injection element 45 include the respective hole injection layers 11, the respective hole transport layers 12, the respective organic layers 13, and the respective electrons. It is a part corresponding to each display element 1 in the transport layer 14 and each electron injection layer 15.
[0031]
The plurality of anodes 3 and the plurality of cathodes 4 are electrically connected to a driver IC (not shown). A scanning voltage is sequentially applied to the plurality of anodes 3 from the driver IC, and a signal voltage corresponding to the display image is input to the plurality of cathodes 4 in synchronization with the clock pulse.
[0032]
When a voltage higher than the threshold is applied between the anode element 33 and the cathode element 34 corresponding to the selected display element 1 by the driver IC, holes are injected from the anode element 33 into the hole injection element 41. Then, electrons are injected from the cathode element 34 into the electron injection element 45. Electrons are transported to the light emitting element 43 via the electron transport element 44 and holes are transported to the light emitting element 43 via the hole transport element 42. In the light emitting element 43, electrons and holes are recombined to generate excitons, and the excitons move through the light emitting element 43. The excitons emit energy corresponding to the band of the luminescent material, so that the luminescent material and thus the light emitting element 43 emits light. As clearly shown in FIG. 2, in the structure of the present invention, light generated in the organic element 40 can be extracted directly from the opening 9 to the second direction side. In this way, the selected display element 1 emits light, and an image is displayed by combining them.
[0033]
In the case where the organic EL display device X is configured for color display, for example, the three adjacent light emitting layers 13 are made up of an R light emitting layer, a G light emitting layer, and a B light emitting layer. A plurality may be provided. In this case, the R light emitting layer, the G light emitting layer, and the B light emitting layer may contain a light emitting substance that emits light corresponding to each color, or emit light filters corresponding to each color. It may be provided on the layer 13.
[0034]
As described above, the configuration in the present embodiment has a structure in which light generated in the organic layer 10 can be extracted directly from the opening 9 to the second direction side. Therefore, in the configuration as shown in FIG. 7, when light is emitted from the second substrate surface 52b, for example, light passes through ITO as the transparent electrode 53 or the glass substrate 52 as the substrate. Although the amount of light that can be extracted is reduced, in the configuration in the present embodiment, light can be emitted from the opening 9 provided in the cathode 4, and thus the reduction in the amount of light is suppressed. In addition, since the light can be taken out without being transmitted through the transparent electrode 53, there is no problem such as a problem that the emitted light is reddish, which may occur when the ITO is transmitted. Stability is also eliminated.
[0035]
Further, in the configuration as shown in FIG. 7, in order to emit light in two directions, the first and second directions, the transparent electrode 53 as the anode and the reflective electrode 54 as the cathode are always made of a transparent material. For example, when ITO or the like is used, the driving voltage is increased as compared with an opaque but relatively low resistivity metal such as copper or aluminum. However, in the configuration of the present embodiment, light can be emitted in the two directions just by making the anode 3 a transparent electrode. For example, if the cathode 4 is made of a metal having a relatively low resistivity, Even with a low driving voltage, light can be emitted in the two directions without unevenness, and the driving voltage can be reduced.
[0036]
Furthermore, in the case of the configuration shown in FIG. 7, the light cannot be emitted to the outside unless one of the transparent electrode 53 and the reflective electrode 54 is a transparent electrode. Even if opaque metal electrodes are used for both the anode 3 and the cathode 4, light can be emitted from the opening 9 in the second direction. For this reason, an opaque but low resistivity material such as copper or aluminum can be used, so that light can be emitted evenly even at a low driving voltage.
[0037]
In this case, a silicon substrate that is opaque but has a high thermal diffusivity can also be used. Therefore, in the case where there is a possibility that the generation of heat becomes large as in the configuration in the present embodiment, by adopting a silicon substrate as the substrate 2, thermal degradation is suppressed and the life of the display device 1 is extended. Is also possible.
[0038]
In the present embodiment, the organic EL display device X in which the organic layer 10 is configured by the hole injection layer 11, the hole transport layer 12, the light emitting layer 13, the electron transport layer 14, and the electron injection layer 15 has been described as an example. The configuration of the organic layer 10 can be variously modified. For example, a two-layer structure including the hole transport layer 12 and the light-emitting layer 13 or an electron transport layer 14 and the light-emitting layer 13 may be used, or a three-layer structure including the hole transport layer 12, the electron transport layer 14 and the light-emitting layer 13. May be.
[0039]
An organic EL display device X ′ according to a second embodiment of the present invention will be described with reference to FIG. In this figure, the same or similar members or elements as those of the organic EL display device X described above are denoted by the same reference numerals, and redundant description thereof will be omitted.
[0040]
As shown in FIG. 6, the organic EL display device X ′ has the same configuration as the organic EL display device X according to the first embodiment of the present invention. In addition, the portion where the organic layer 10 is exposed through the opening 9 provided in the cathode 4 is covered with a light-transmitting metal conductor layer 20, and the metal conductor layer 20 is in contact with the cathode 4. It is configured as follows.
[0041]
The metal conductor layer 20 is formed of a metal such as gold or aluminum so that the thickness is 50 nm or less. By setting the thickness to 50 nm or less, it is possible to secure a light-transmitting property in visible light and to compensate for a decrease in the contact area between the organic layer 10 and the cathode 4 due to the provision of the opening 9 in the cathode 4. Therefore, it is possible to improve the electron injection efficiency and reduce the driving voltage by lowering the resistance of the cathode 4. Further, the determination of the area where the metal conductor layer 20 covers the organic layer 10 can be freely selected from the viewpoints of the amount of light emitted from the opening 9, the electron injection efficiency, the driving voltage, and the ease of manufacturing.
[0042]
In the second embodiment, the same design change as in the first embodiment can be made.
[Brief description of the drawings]
1A and 1B are a cross-sectional view and a cutaway perspective view showing an example of an organic EL display device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II of FIG.
FIG. 3 is a fragmentary perspective view for explaining a cathode forming step of the organic EL display device according to the first embodiment of the present invention.
4 is a fragmentary perspective view for explaining a cathode forming step of the organic EL display device according to the first embodiment of the present invention. FIG.
FIG. 5 is a cutaway perspective view for explaining a cathode forming step of the organic EL display device according to the first embodiment of the present invention.
6 is an example of an organic EL display device according to a second embodiment of the present invention, and is a cross-sectional view of a portion corresponding to a cross-sectional view taken along line II in FIG. 1. FIG.
FIG. 7 is a cross-sectional view showing an example of a conventional organic EL display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Element 2 Board | substrate 3 1st electrode 4 2nd electrode 9 Opening part 20 Metal conductor layer 33 1st electrode element 34 2nd electrode element 40 Organic element 43 Light emitting element X, X ', X "Organic EL display apparatus

Claims (5)

A plurality of display elements provided on a substrate, and each of these display elements is stacked in this order, a first electrode element, an organic element having a light emitting element that emits light by applying an electric field, and a second electrode element An organic EL display device having a formed form,
A plurality of the first electrode elements are arranged in a row aligned in the first direction, are formed in a strip shape extending in the first direction, and are arranged in parallel in a second direction orthogonal to the first direction. In addition, the plurality of first electrodes and the plurality of second electrode elements are arranged in rows arranged in the second direction and are formed in a strip shape extending in the second direction, and are parallel to the first direction. A plurality of second electrodes arranged; and
Each of the portions of the second electrodes intersecting with the plurality of first electrodes is formed with one rectangular window hole-shaped opening, and light generated by the light emitting element is emitted from each of the openings. While being emitted ,
At least a part of the organic element is covered with a light-transmitting metal conductor layer, and the metal conductor layer is at least partly in contact with the second electrode element. .   The organic EL display device according to claim 1, wherein the substrate and the first electrode element are formed to have translucency. The metal conductive layer, the thickness of gold or aluminum is formed on the 50nm or less, the organic EL display device according to claim 1 or 2. The opening is rectangular or substantially rectangular,
The dimensions of the second direction in the opening, the first is smaller than the dimension of the second direction of the electrode, the organic EL display device according to any one of claims 1 to 3. A plurality of display elements provided on a substrate, and each of these display elements is stacked in this order, a first electrode element, an organic element having a light emitting element that emits light by applying an electric field, and a second electrode element A plurality of the first electrode elements are arranged in a row aligned in the first direction, are formed in a strip shape extending in the first direction, and are orthogonal to the first direction. A plurality of first electrodes arranged in parallel in the second direction and a plurality of the second electrode elements are arranged in a row aligned in the second direction and formed in a strip shape extending in the second direction, And a plurality of second electrodes arranged in parallel in the first direction, and each of the portions of the second electrodes intersecting with the plurality of first electrodes has one rectangular window. Organic with hole-shaped openings A method of manufacturing a L display device,
The plurality of second electrodes in which the openings are formed include a first step of forming narrow strips on both sides in the width direction of the second electrodes, and a portion connecting the narrow strips so as to sandwich the openings. And a second step of forming the organic EL display device.

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