JP2008218330A - Organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device having a high numerical aperture while lowering effectual electrode wiring resistance of an electrode on the upper side. <P>SOLUTION: The organic EL display device has a display part DYP comprising a plurality of display pixels PX disposed in a matrix shape on a substrate GL. The display part DYP includes first electrodes E1 disposed on the substrate GL side in each of the display pixels PX, second electrodes E2 facingly disposed to the plurality of the first electrodes E1, organic layers 5 held between the first electrodes E1 and second electrodes E2, and conductive reflecting layers RE disposed between the substrate GL and the first electrodes E1. The second electrode E2 is electrically connected to the conductive reflecting layer RE. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic EL display device, and more particularly to a top emission organic EL display device.

  The demand for flat display devices typified by liquid crystal display devices is rapidly increasing for CRT displays by making use of the features of thinness, light weight and low power consumption. Among them, an active matrix type flat display device in which a switch element is provided for each display element can obtain a good display quality without crosstalk between adjacent display elements. Has come to be used.

  In recent years, organic electroluminescence (EL) display devices have been actively developed as self-luminous displays capable of high-speed response and wide viewing angle as compared with liquid crystal display devices.

  The organic EL display device includes an organic EL display panel and an external drive circuit that drives the organic EL display panel. An organic EL display panel has a first electrode, a second electrode arranged opposite to the first electrode, and a display element having an organic light emitting layer between the electrodes arranged in a matrix on a support substrate such as glass. And a drive circuit region for driving each display element based on a signal from an external drive circuit.

  As a method of using EL light emission of this organic EL display device for display, there are a bottom emission method in which light is led out through a support substrate and a top emission method in which light is led out to the side facing the support substrate.

  In an active matrix type bottom emission type organic EL display device, a circuit such as a thin film transistor (TFT) that blocks transmission of EL light emission is disposed below the organic light emitting layer, so that it is difficult to ensure a sufficient aperture ratio. . Since the organic EL display device of the top emission type derives EL light emission on the side facing the support substrate, the aperture ratio is determined without being restricted by the circuit disposed on the support substrate side. Securement is possible.

In the top emission method, a reflective structure is provided on the lower side (substrate side) of the organic EL element to guide light upward, or the upper side is normally configured to transmit light through a transparent electrode (see Patent Document 1).
JP 2006-1000018 A

  By the way, in order to increase the transmittance of the upper transparent electrode, it is necessary to use a thin film material having a good transmittance and to reduce the film thickness when the thin film material has light absorption. Therefore, for example, when manufacturing a large-screen display, it has been difficult to ensure sufficient electrical conductivity as an electrode of an organic EL element. Therefore, a technique for reducing the resistance of the upper electrode has been demanded.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic EL display device having a high aperture ratio while reducing the effective electrode wiring resistance of the upper electrode. .

  A liquid crystal display device according to an aspect of the present invention includes a display unit including a plurality of display pixels arranged in a matrix on a substrate, and the display unit is a first unit arranged on the substrate side in each of the display pixels. An electrode, a second electrode disposed to face the plurality of first electrodes, an organic layer sandwiched between the first electrode and the second electrode, the substrate and the first electrode A conductive reflective layer disposed therebetween, and the second electrode and the conductive reflective layer are electrically connected.

  According to the present invention, it is an object to provide an organic EL display device having a high aperture ratio while reducing the effective electrode wiring resistance of the upper electrode.

  The organic EL display device according to the first embodiment of the present invention will be described below with reference to the drawings. The EL display device according to the present embodiment is a top emission type organic EL display device, and as shown in FIG. 1, an array substrate 100 and a sealing substrate 200 disposed to face the array substrate 100. have.

  As shown in FIG. 2, the array substrate 100 has an insulating substrate GL such as glass as a support substrate. The array substrate 100 has a display unit DYP including a plurality of display pixels PX arranged in a matrix on the insulating substrate GL.

  In the display unit DYP, the scanning lines Y (Y1, Y2,...) Arranged along the rows in which the display pixels PX are arranged and the signal lines X (in the columns in which the display pixels PX are arranged are arranged. X1, X2,...) Are arranged.

  In the outer peripheral part PA surrounding the display part DYP, the array substrate 100 has a scanning line drive circuit (not shown) for driving each display pixel based on a signal from the external drive circuit, a signal line drive circuit (not shown), and the like. The driving circuit unit 101 having

  Further, the outer peripheral portion PA has a connection portion 102 for connecting an external circuit such as a controller. Various wirings W for supplying a drive signal, a power supply signal, and the like extend between the drive circuit unit 101 and the display unit DYP.

  The scanning line driving circuit is electrically connected to the scanning line Y through the wiring W, and sequentially drives the display pixels PX row by row. The signal line driving circuit is electrically connected to the signal line X through various wirings W, and transmits an image signal to the display pixel PX driven by the scanning line Y.

  Further, a power supply line P extending substantially parallel to the scanning line Y is disposed on the display unit DYP of the array substrate 100. The display pixel PX has a first switch 10 connected to the scanning line Y at its gate electrode, and a second switch 20 whose gate electrode is connected to the drain electrode of the first switch 10.

  The source electrode of the second switch 20 is connected to the power supply line P, and the drain electrode of the second switch 20 is connected to the light emitting element 40. The gate electrode and the source electrode of the second switch 20 are coupled by a capacitor 30.

  The display pixel PX includes display pixels PXR, PXG, and PXB having any one of the light emitting elements 40 (R, G, and B) that are self-light emitting elements. That is, the red pixel PXR includes an organic EL element 40R that mainly emits light corresponding to the red wavelength. The green pixel PXG includes an organic EL element 40G that mainly emits light corresponding to the green wavelength. The blue pixel PXB includes an organic EL element 40B that mainly emits light corresponding to the blue wavelength.

  As shown in FIG. 2, TFT layers LT such as the first switch 10 and the second switch 20 are disposed on the insulating substrate GL. On the TFT layer LT, the conductive reflective layer RE is disposed via the insulating layer L1. As shown in FIGS. 2 and 3, the conductive reflective layer RE is shared by the plurality of display pixels PX.

  A first electrode E1 is disposed on the conductive reflective layer RE via a planarizing layer L2. For the first electrode E1, for example, ITO, which is a transparent electrode material, is used. A rib layer LIB is disposed on the first electrode E1. The rib layer LIB is formed of, for example, a resin and is disposed so as to overlap with a region where the signal line X and the scanning line Y are disposed.

  While the rib layer LIB is disposed, the organic layer 5 is disposed on the first electrode E1. The organic layer 5 includes, for example, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. On the organic layer 5, the second electrode E2 is disposed. The second electrode E2 is a transparent electrode formed of, for example, a Mg: Ag alloy having a thickness of about 20 nm.

  That is, the organic layer 5 emits light by a voltage applied between the first electrode E1 and the second electrode E2. At this time, the light emitted from the organic layer 5 to the first electrode E1 side is reflected by the conductive reflective layer RE to the second electrode E2 side.

  As described above, the organic EL display device according to the present embodiment has a so-called top emission structure in which the light emitted from the organic EL display device is derived and emitted toward the surface opposite to the substrate GL.

  In the organic EL display device according to the present embodiment, the second electrode E2 is electrically connected to the conductive reflective layer RE through a contact hole CH provided in the planarization layer L2. That is, as shown in FIG. 2, the planarization layer L2 has a contact hole CH on the conductive reflective layer RE in a region between adjacent display pixels PX. Therefore, in the organic EL display device according to the present embodiment, the contact hole CH is provided between the rib layers LIB arranged around the adjacent display pixels PX.

  The surface of the contact hole CH is covered with the first electrode E1 disposed in the upper layer. The second electrode E2 is electrically connected to the conductive reflective layer RE via the first electrode E1.

  As described above, since the first electrode E1 is disposed between the conductive reflective layer RE and the second electrode E2 in the contact hole CH, the slope of the slope of the contact hole CH becomes gentle, and the second electrode It becomes possible to prevent defects such as disconnection when E2 is made sufficiently thin. Furthermore, by covering the conductive reflective layer RE with the first electrode E1, the first electrode E1 and the conductive reflective layer RE are protected from an etching solution or the like used in the manufacturing process.

  As described above, the resistance of the second electrode E2 can be reduced by connecting the second electrode E2 to the conductive reflective layer RE. Therefore, according to the organic EL display device according to this embodiment, even when the second electrode E2 is sufficiently thin, it is possible to suppress an increase in resistance.

  That is, according to the organic EL display device according to the present embodiment, since the light transmittance of the second electrode E2 can be kept high, the aperture ratio of the organic EL display device can be increased.

  The sealing substrate 200 is disposed so as to face the array substrate 100 in the display unit DYP. The array substrate 100 and the sealing substrate 200 are integrated by a sealing material SL disposed so as to surround the display unit DYP. In the EL display device according to the present embodiment, a resin seal made of a resin material is used as the seal material SL.

  The sealing substrate 200 is disposed in a region surrounded by the sealing material SL so as to face the display portion DYP of the array substrate 100 and has a recess (not shown). In the EL display device according to the present embodiment, the recess is substantially rectangular, and the recess is filled with a desiccant (not shown).

  Next, a method for manufacturing the organic EL display device according to this embodiment will be described. A TFT layer LT such as a switch 10 or 20 such as a TFT is formed on an insulating substrate GL such as glass, and an insulating layer L1 is formed on the TFT layer LT.

  On the insulating layer L1, a conductive reflective layer RE is formed by depositing and patterning a metal or the like mainly composed of aluminum (Al) or silver (Ag). Further, on the conductive reflective layer RE, for example, an acrylic transparent photosensitive resin is formed to form a flattening layer L2 for smoothing the surface. At this time, contact holes CH are formed by patterning at positions where the planarizing layer L2 is disposed on the conductive reflective layer RE.

  Then, after the first electrode E1 is formed of, for example, ITO, which is a transparent anode electrode material, on the planarizing layer L2, the rib layer LIB is formed of an insulating material in order to prevent a short circuit other than the display pixel PX. .

  That is, the planarization layer L2 ensures insulation between the conductive reflective layer RE and the first electrode E1. It is also possible to adjust the light emission interference condition (cavity effect) of the organic layer 5 by the film thickness of the planarizing layer L2.

  On the first electrode E1, for example, an organic layer 5 including a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer is formed. On the organic layer 5, for example, a translucent Mg: Ag alloy having a thickness of about 20 nm is formed as the second electrode E2.

  Therefore, as shown in FIG. 2, in the contact hole CH, the first electrode E1 and the second electrode E2 are formed on the conductive reflective layer RE in this order. This is, for example, in the case of a laminated film of aluminum, ITO, and Mg: Ag in order to avoid electrolytic corrosion of the aluminum due to the battery reaction during the etching process of the ITO. do it.

  In the organic EL display device manufactured as described above, the wiring resistance of the second electrode E2 can be lowered by connecting the second electrode E2 and the conductive reflective layer RE.

  In the case where a plurality of display pixels PX are formed on the substrate GL as in the EL display device according to the present embodiment, the effect is obtained by forming the conductive reflective layer RE over the plurality of display pixels PX. Therefore, the wiring resistance can be lowered.

  Rather than using the conductive reflective layer RE divided into small parts, the resistance can be reduced by forming it two-dimensionally. Furthermore, it is possible to reduce the resistance by increasing the number of through holes.

  In the organic EL display device according to the present embodiment, when the contact hole for electrically connecting the drain electrode of the switch 20 arranged in the TFT layer LT and the first electrode E1 is formed in the planarization layer L2. In addition, since the contact hole CH can be formed at the same time, the effective electrode wiring resistance of the upper electrode can be reduced without increasing the number of manufacturing steps, and an organic EL display device having a high aperture ratio can be provided. .

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.

  For example, in the liquid crystal display device according to the above embodiment, the conductive reflective layer RE is a single layer common to the plurality of display pixels PX as shown in FIG. As shown, it may be a plurality of lines. Furthermore, as shown in FIG.

  As described above, the resistance of the second electrode E2 can be lowered by spreading the conductive reflective layer RE two-dimensionally. However, as shown in FIGS. 5 and 6, the conductive reflective layer RE is divided. Thus, for example, the occurrence of short circuit failure between the conductive reflective layer RE and the first electrode E1 is suppressed, or the signal writing characteristics are improved by reducing the parasitic capacitance between the conductive reflective layer RE and the image signal wiring. You can make it.

  Therefore, by changing the design in relation to the resistance value of the second electrode E2, the same effect as that of the EL display device according to the first embodiment described above can be obtained, and in addition, problems due to short circuits and image signal writing characteristics can be reduced. An EL display device that can be improved can be provided.

  In the EL display device according to the first embodiment described above, one contact hole is provided in one display pixel PX. For example, as shown in FIG. 4, a plurality of contacts are provided in one display pixel PX. A hole CH may be provided, and one contact hole CH may be enlarged. That is, as shown in FIG. 4, the resistance of the second electrode E2 can be further reduced by increasing the area where the second electrode E2 and the conductive reflective layer RE are electrically connected.

  Furthermore, in the organic EL display device according to the above embodiment, the barrier metal in the same layer as the first electrode E1 is disposed between the conductive reflective layer RE and the second electrode E2 in the contact hole CH. The barrier metal disposed between the conductive reflective layer RE and the second electrode E2 may be, for example, a conductive layer such as molybdenum (Mo), titanium (Ti), or tungsten (W). Even in that case, the same effect as the organic EL display device according to the above-described embodiment can be obtained.

  Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

1 is a diagram schematically showing a configuration example of an organic EL display device according to an embodiment of the present invention. FIG. 2 is a diagram schematically illustrating a configuration example of a cross section of a display pixel of the organic EL display device illustrated in FIG. 1. FIG. 2 is a diagram schematically showing a configuration example of a conductive reflective layer and contact holes of the organic EL display device shown in FIG. 1. The figure which shows schematically the other structural example of the electroconductive reflection layer and contact hole of the organic electroluminescent display apparatus shown in FIG. The figure which shows schematically the other structural example of the electroconductive reflection layer and contact hole of the organic electroluminescent display apparatus shown in FIG. The figure which shows schematically the other structural example of the electroconductive reflection layer and contact hole of the organic electroluminescent display apparatus shown in FIG.

Explanation of symbols

  PX ... display pixel, DYP ... display unit, RE ... conductive reflective layer, E1 ... first electrode, E2 ... first electrode, GL ... substrate, 5 ... organic layer, 100 ... array substrate

Claims (4)

A display unit including a plurality of display pixels arranged in a matrix on a substrate;
The display unit includes a first electrode disposed on the substrate side in each of the display pixels, a second electrode disposed opposite to the plurality of first electrodes, the first electrode, and the second electrode. An organic layer sandwiched between, and a conductive reflective layer disposed between the substrate and the first electrode,
An organic EL display device in which the second electrode and the conductive reflective layer are electrically connected. An insulating layer is disposed between the second electrode and the conductive reflective layer;
The organic EL display device according to claim 1, wherein the second electrode and the conductive reflective layer are electrically connected through a contact hole provided in the insulating layer.   The organic EL display device according to claim 1, wherein the conductive reflective layer is shared by at least two or more display pixels.   4. The organic EL display device according to claim 1, wherein an electrical connection portion between the conductive reflective layer and the second electrode is connected via another conductive material. 5.

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