JP2008234928A - Organic electroluminescent display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate pattern size control in each layer after forming an optical modulation layer and to provide an organic EL display apparatus with high efficiency in extracting light. <P>SOLUTION: An organic EL display apparatus is provided with display pixels PX installed in a matrix state on a substrate GL. The organic EL display apparatus is provided with first electrodes E1 installed on the substrate GL side in each respective display pixels PX, second electrodes E2 installed to face the plurality of first electrodes E1, organic layers 5 held between the first electrodes E1 and the second electrodes E2, a light modulation layer RE with a structure varying optical paths of light emitted from the organic layers 5. Edges of a layer installed on an upper layer of the light conversion layer RE, are installed outside a range AR in which the light modulation layer RE is installed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic EL display device, and more particularly to an active matrix type 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.

The light generated in the light emitting layer is confined in the layer due to total reflection due to the difference in refractive index of each layer constituting the element, and it is difficult to extract all the light from the organic EL display device. However, a method for improving the light extraction efficiency has been studied. For example, it is possible to extract confined light by changing the optical path.
JP 2005-310539 A

  However, by creating a structure that changes the optical path (hereinafter referred to as a light modulation layer), a problem arises in patterning that is subsequently formed. Since this is a process in which photolithography uses light, it is difficult to control the pattern dimensions by bending the optical path of the exposure. Therefore, there has been a demand for a technique that makes it easy to control the pattern dimensions of each layer after forming the light modulation layer.

  The present invention has been made in view of the above problems, and provides an organic EL display device that facilitates control of the pattern dimensions of each layer after formation of a light modulation layer and has high light extraction efficiency. With the goal.

  A liquid crystal display device according to an aspect of the present invention is an organic EL display device having display pixels arranged in a matrix on a substrate, and each of the display pixels includes a first electrode arranged on the substrate side, and a plurality of display pixels A second electrode disposed so as to face the first electrode; an organic layer sandwiched between the first electrode and the second electrode; and a structure for changing an optical path of light emitted from the organic layer The edge of the layer disposed above the light modulation layer is disposed outside the region where the light modulation layer is disposed.

  ADVANTAGE OF THE INVENTION According to this invention, control of the pattern dimension of each layer after light modulation layer formation is easy, and an organic electroluminescent display apparatus with high light extraction efficiency can be provided.

  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.

  The array substrate 100 and the sealing substrate 200 are integrated by a sealing material SL as shown in FIG. 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).

  As shown in FIGS. 1 and 2, the array substrate 100 includes 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, an uneven layer L2 is disposed via an insulating layer L1. The concavo-convex layer L2 has dot-like convex portions on the surface thereof. In the organic EL display device according to this embodiment, the pitch at which the convex portions are arranged is about 10 μm, and the height difference between the convex portions and the concave portions is about 1 μm.

  On the uneven layer L2, a reflective layer RE is disposed as a light modulation layer. The reflective layer RE has an uneven shape that follows the shape of the uneven layer L2. On the reflective layer RE, the first electrode E1 is disposed via the planarization layer L3. The first electrode E1 is electrically connected to the TFT layer LT in a contact hole CH provided in the insulating layer L1 and the planarization layer L3.

  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, resin, and is disposed so as to overlap with a part of a region where the signal line X and the scanning line Y are disposed, for example.

  The organic layer 5 is disposed on the first electrode E1 between the rib layers LIB. 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 to the second electrode E2 side by the reflective layer RE (light modulation layer). That is, the reflective layer RE is a light modulation layer that changes the optical path of the light emitted from the organic layer 5 depending on the shape of the surface thereof.

  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, as shown in FIG. 2, the edge of the layer disposed above the reflective layer RE is disposed outside the region AR where the reflective layer RE is disposed. That is, no edges such as the first electrode E1 and the rib layer LIB are disposed on the reflective layer RE.

  As described above, by not arranging the edge of the layer disposed above the reflective layer RE in the area AR, in the manufacturing process of the organic EL display device described below, the pattern dimension of the layer above the reflective layer RE is increased. Since the control is facilitated, the light reflected by the reflective layer RE is not obstructed by the edge of the upper layer of the reflective layer RE.

  Therefore, according to the organic EL display device described above, the efficiency (light extraction efficiency) of deriving the light emitted from the organic layer 5 to the second electrode E2 side can be improved.

  Next, a method for manufacturing the organic EL display device will be described. First, the insulating layer L1 is formed on the substrate 1 on which the TFT layers such as the switches 10 and 20 are formed on the transparent insulating substrate GL such as glass.

  On the insulating layer L1, for example, a photosensitive resin is applied, and the uneven layer L2 is formed by patterning into a predetermined shape by photolithography. In the organic EL display device according to the present embodiment, dot-shaped convex portions are formed at a pitch of 10 μm on the surface of the concave-convex layer L2, and the height difference between the concave portions and the convex portions is 1 μm.

  On the uneven layer L2, the reflective layer RE is formed of a metal or the like mainly composed of aluminum (Al) or silver (Ag). In the organic EL display device according to this embodiment, the reflective layer RE functions as a light modulation layer that bends the optical path.

  That is, as described above, since the organic EL display device according to the present embodiment is a top emission type organic EL display device, the light emitted from the organic layer 5 is reflected to the upper layer side in the reflective layer RE. . Therefore, in the following patterning process, no pattern edge is arranged in the area AR in which the reflective layer RE formed on the uneven layer L2 is arranged.

  Thereby, since it is not influenced by a light modulation layer, control of a pattern dimension can be performed easily. In addition, in the case of a layer that leaves a film on the light modulation layer, a positive photosensitive resin from which a portion irradiated with light is removed is used. In the case of a layer that does not leave a film, a negative that cures by irradiation with light. By patterning using the photosensitive resin of the mold, the influence on the pattern dimension control by the light modulation layer can be further suppressed.

  That is, on the reflective layer RE, a flattened layer L3 for smoothing the surface with an acrylic transparent photosensitive resin or the like is formed. On the planarizing layer L3, a transparent electrode is formed as the first electrode E1, for example, ITO, which is a transparent anode electrode material.

  On the first electrode E1, a rib layer LIB is formed of an insulating material in order to prevent a short circuit other than in the light emitting portion. On the rib layer LIB, an organic layer 5 made of, for example, 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 semitransparent film having a thickness of about 20 nm is formed. A transparent electrode made of Mg: Ag alloy is formed as the second electrode E2.

  In the organic EL display device formed as described above, the light emitted from the organic layer 5 is modulated by modulating the optical path of the light emitted from the organic layer 5 by the reflective layer RE formed on the uneven layer L2. The efficiency derived to the outside (light extraction efficiency) can be improved.

  And in the formation area of a light modulation layer, the layer formed on it does not have a pattern edge on a light modulation layer, Therefore The control of the pattern dimension of each layer can be made easy.

  That is, according to the organic EL display device according to the present embodiment, it is possible to easily control the pattern size of each layer disposed on the light modulation layer and to provide an organic EL display device with high light extraction efficiency. it can.

  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, the organic EL display device according to the above-described embodiment includes the reflective layer RE disposed on the uneven layer L2 as the light modulation layer, but the light modulation layer is not limited thereto. For example, the light modulation layer may have any structure that changes the optical path, such as a diffraction grating.

  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.

Explanation of symbols

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

Claims (3)

An organic EL display device having display pixels arranged in a matrix on a substrate,
A first electrode disposed on the substrate side in each of the display pixels;
A second electrode disposed to face the plurality of first electrodes;
An organic layer sandwiched between the first electrode and the second electrode;
A light modulation layer having a structure for changing an optical path of light emitted from the organic layer,
An organic EL display device in which an edge of a layer disposed above the light modulation layer is disposed outside a region where the light modulation layer is disposed.   The concavo-convex layer whose surface has an uneven shape is disposed under the light modulation layer, and the surface of the light modulation layer has an uneven shape according to the shape of the surface of the uneven layer. Organic EL display device.   2. The organic material according to claim 1, wherein the light modulation layer is a reflective layer that is disposed between the substrate and the first electrode and reflects light emitted from the organic layer to a side opposite to the substrate. EL display device.

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