Organic electroluminescent display device and method for manufacturing the same

An organic electroluminescent display device includes a substrate, plural pixel electrodes that are disposed on the substrate, an insulating layer that is disposed in areas between the pixel electrodes adjacent to each other, and extends integrally to upper and lower portions of ends of the pixel electrodes adjacent to each other, an organic electroluminescent film that is disposed on the substrate with the inclusion of a common layer that continuously covers the plural pixel electrodes and the insulating layer; and a common electrode that is disposed on the organic electroluminescent film.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2013-186141 filed on Sep. 9, 2013, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electroluminescent display device, and a method for manufacturing the same.

2. Description of the Related Art

An organic electroluminescent display device has a structure in which an organic film is sandwiched between an anode and a cathode (refer to JP 2012-234748 A). As usual, plural organic films are laminated on each other, and one of those organic films is a light emitting layer. In order to obtain light emission of one color (for example, white) in plural pixels, the organic film for making the light emitting layer is wholly continuously formed (refer to JP 2008-123879 A). Alternatively, in order to obtain the light emission of plural colors in the plural pixels, the organic film for making the light emitting layer is separated for each of pixels, but the organic film for making a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, or the like is continuously formed. Even in any case, at least one organic film is continuously formed over the pixels adjacent to each other.

SUMMARY OF THE INVENTION

In a high-quality display device, the pixels adjacent to each other come closer to each other by miniaturization of the pixels. For that reason, a light generated in any pixel may penetrate to the adjacent pixels. If colors of the pixels adjacent to each other are different from each other, there arises such a problem that the colors are mixed together. JP 2012-234748 A and JP 2008-123879 A fail to disclose the problem on the color mixture.

The present invention relates to the prevention of color mixture in pixels adjacent to each other.

(1) According to the present invention, there is provided an organic electroluminescent display device, including: a substrate; a plurality of pixel electrodes that are disposed on the substrate; an insulating layer that is disposed in areas between the pixel electrodes adjacent to each other, and extends integrally to upper and lower portions of ends of the pixel electrodes adjacent to each other; an organic electroluminescent film that is disposed on the substrate with the inclusion of a common layer that continuously covers the plurality of pixel electrodes and the insulating layer; and a common electrode that is disposed on the organic electroluminescent film. According to the present invention, since the insulating layer rests on the ends of the pixel electrodes, short-circuiting between the ends of the pixel electrodes and the common electrode can be prevented. The insulating layer extends integrally to the upper and lower portions of the ends of the pixel electrodes. For that reason, since the insulating layer can be thinly formed on the ends of the pixel electrodes, a curvature of the organic electroluminescent film toward a swelling direction thereof can be reduced. With this configuration, since light that has penetrated to the adjacent pixels hardly travels upward, the color mixture of the pixels adjacent to each other can be prevented.

(2) In the organic electroluminescent display device according to the item (1), the insulating layer may have a concave portion recessed in an upper surface thereof, and the common layer may be curved along the concave portion.

(3) In the organic electroluminescent display device according to the item (2), a bottom surface of the concave portion of the insulating layer may be located at a position lower than upper surfaces of the plurality of pixel electrodes, and a lower surface of the common layer may be located at a position lower than the upper surfaces of the plurality of pixel electrodes above the concave portion of the insulating layer.

(4) In the organic electroluminescent display device according to the item (2) or (3), the common electrode may be curved along a curvature of the common layer, the organic electroluminescent display device may further include a sealing layer that conducts sealing to cover the organic electroluminescent film and the common electrode, and a lower surface of the sealing layer may have irregularity along the curvature of the common layer.

(5) In the organic electroluminescent display device according to the item (4), the sealing layer may include a plurality of layers, a lowermost layer of the sealing layer may be curved along the curvature of the common electrode, and an uppermost layer of the sealing layer may be flat on an upper surface thereof.

(6) In the organic electroluminescent display device according to any one of the items (1) to (5), a wiring layer may be disposed over the substrate below the plurality of pixel electrodes, and each of the pixel electrodes may have a connection portion extended downward so as to be connected to the wiring layer.

(7) In the organic electroluminescent display device according to the item (6), the connection portion may be disposed to be bent toward the wiring layer with the avoidance of the ends of the pixel electrodes, and the insulating layer may be disposed to extend from the ends to an upper portion of the connection portion.

(8) In the organic electroluminescent display device according to the item (6), the connection portion may be bent toward the wiring layer with the inclusion of the ends of the pixel electrodes.

(9) According to the present invention, there is provided a method for manufacturing an organic electroluminescent display device, including the steps of: forming an underlying layer on a substrate; forming a conductive layer on the underlying layer; patterning the conductive layer into a shape of a plurality of pixel electrodes; patterning the underlying layer so as to overhang ends of the plurality of pixel electrodes; forming an insulating layer to cover the plurality of pixel electrodes and the underlying layer so as to extend between the pixel electrodes adjacent to each other, and below the ends of the plurality of pixel electrodes; patterning the insulating layer so as to expose at least center portions of the respective pixel electrodes except for the ends thereof; forming an organic electroluminescent film with the inclusion of a common layer that continuously covers exposed areas of the plurality of pixel electrodes from the insulating layer, and the insulating layer; and forming a common electrode on the organic electroluminescent film. According to the present invention, since the insulating layer rests on the ends of the pixel electrodes, short-circuiting between the ends of the pixel electrodes and the common electrode can be prevented. The insulating layer extends integrally to the upper and lower portions of the ends of the pixel electrodes without conducting a complicated step such as half exposure.

(10) The method for manufacturing an organic electroluminescent display device according to the item (9) may further include the step of forming a mask layer having the shape of the plurality of pixel electrodes on the conductive layer before patterning the conductive layer, in which a portion of the conductive layer exposed from the mask layer may be removed in the step of patterning the conductive layer.

(11) In the method for manufacturing an organic electroluminescent display device according to the item (10), a portion of the insulating layer exposed from the mask layer may be removed in the step of patterning the insulating layer.

(12) In the method for manufacturing an organic electroluminescent display device according to the item (10), a portion of the insulating layer exposed from the plurality of pixel electrodes may be removed after removing the mask layer in the step of patterning the insulating layer.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a perspective view of an organic electroluminescent display device according to an embodiment of the present invention. The organic electroluminescent display device includes a first substrate10having an optical transparency made of glass or the like. The first substrate10has an image display area for image display. An integrated circuit chip12for driving elements for displaying an image is mounted on the first substrate10. The first substrate10is connected with a flexible wiring substrate14for electric connection with an external.

FIG. 2is a partially enlarged plan view of the organic electroluminescent display device illustrated inFIG. 1. Plural pixel electrodes16are disposed on the first substrate10. The pixel electrodes16form anodes. The plural pixel electrodes16are arrayed in a vertical direction and a horizontal direction. An insulating layer18is so disposed as to rest on ends of the pixel electrodes16. The insulating layer18is configured to surround the peripheries of the respective pixel electrodes16. In other words, the insulating layer18has openings18afrom which center portions of the pixel electrodes16are exposed.

FIG. 3is a cross-sectional view of the organic electroluminescent display device taken along a line III-III illustrated inFIG. 2.FIG. 4is a cross-sectional view of the organic electroluminescent display device taken along a line IV-IV illustrated inFIG. 2.

The first substrate10is formed with an undercoat20that functions as a barrier against impurities from the first substrate10, and a semiconductor layer22is formed on the undercoat20. A gate insulating film24is formed to cover the semiconductor layer22. A gate electrode26is formed on the gate insulating film24, and an interlayer insulating film28is formed to cover the gate electrode26. Plural wiring layers30are disposed on the first substrate10(on the interlayer insulating film28). Apart of the wiring layers30penetrates through the interlayer insulating film28, and functions as a source electrode or a drain electrode on the semiconductor layer22, and forms a thin film transistor. A passivation film32is formed on the interlayer insulating film28so as to cover the wiring layers30. Since an upper surface of the passivation film32becomes irregular, an underlying layer34is formed for the purpose of planarizing the passivation film32. The underlying layer34is made of resin such as acrylic resin.

The pixel electrodes16are disposed on the underlying layer34. The pixel electrodes16form anodes. The wiring layers30are disposed below the plural pixel electrodes16. As illustrated inFIG. 4, each of the pixel electrodes16has a connection portion16aextending downward so as to be connected to the wiring layer30. The connection portion16ais disposed to be bent toward the wiring layer30with the avoidance of the end of each pixel electrode16. The pixel electrodes16each penetrate through the underlying layer34, and are electrically connected to the wiring layers30.

The underlying layer34has a hole34a(for example, through-hole) between the pixel electrodes16adjacent to each other. The hole34ais shaped to enter a lower portion of the end of each pixel electrode16. That is, the end of the pixel electrode16is overhung from the opening of the hole34a. As illustrated inFIG. 4, the underlying layer34has a partition part36between the hole34aformed between the pixel electrodes16adjacent to each other, and the connection portion16aof one pixel electrode16.

The insulating layer18is disposed in the hole34aof the underlying layer34. The insulating layer18is disposed between the pixel electrodes16adjacent to each other. The insulating layer18extends below the end of the pixel electrode16. Also, the insulating layer18rests on the end of the pixel electrode16. That is, the insulating layer18extends integrally to upper and lower portions of the ends of the pixel electrodes16adjacent to each other. Further, as illustrated inFIG. 4, the insulating layer18extends from the end of the pixel electrode16to the upper portion of the connection portion16a.

An organic electroluminescent film38is disposed over the first substrate10. The organic electroluminescent film38is configured to rest on the plural pixel electrodes16and the insulating layer18. The organic electroluminescent film38is formed of plural layers although not shown, includes at least a light emitting layer, and further includes at least one layer of an electron transport layer, a hole transport layer, an electron injection layer, and a hole injection layer. The light emitting layer is configured to emit only a light of one color (for example, white).

The organic electroluminescent film38includes a common layer40that continuously covers the plural pixel electrodes16and the insulating layer18. In an example illustrated inFIGS. 2 and 3, the overall organic electroluminescent film38forms the common layer40. Alternatively, at least one layer (except for at least one layer) of the organic electroluminescent film38formed of the plural layers may be formed by the common layer40(for example, the electron injection layer), and the remaining layers formed of at least one layer may be cut for each of the pixel electrodes16. In the organic electroluminescent film with a tandem structure including two or more light emitting layers, a charge generation layer for supplying electrons and holes which is arranged between the light emitting layers adjacent to each other may be formed by the common layer40.

A common electrode42is disposed on the organic electroluminescent film38. The common electrode42is a cathode. A voltage is applied to the pixel electrodes16and the common electrode42to inject holes and electrons into the organic electroluminescent film38from the respective electrodes16and42. The injected holes and electrons are coupled together in the light emitting layer to emit a light. Since the insulating layer18is interposed between the end of the pixel electrode16and the common electrode42, short-circuiting between the pixel electrode16and the common electrode42is prevented.

According to this embodiment, since the insulating layer18rests on the ends of the pixel electrodes16, short-circuiting between the ends of the pixel electrodes16and the common electrode42can be prevented. The insulating layer18extends integrally to the upper and lower portions of the ends of the pixel electrodes16. For that reason, since the insulating layer18can be thinly formed on the ends of the pixel electrodes16, a curvature of the organic electroluminescent film38toward a swelling direction thereof can be reduced. With this configuration, since light that has penetrated to the adjacent pixels hardly travels upward, the color mixture of the pixels adjacent to each other can be prevented.

A sealing layer44is disposed on the common electrode42. The sealing layer44seals the organic electroluminescent film38so as to block moisture. A filler layer46is disposed on the sealing layer44.

A second substrate48is arranged to face the first substrate10at an interval. A color filter50is disposed on a surface of the second substrate48on the first substrate10side. The color filter50includes a black matrix52and a colored layer54. Since a light emitting layer (not shown) of the above organic electroluminescent film38emits the light of a single color (for example, white), the color filter50is provided to enable full color display in this embodiment. When the organic electroluminescent film38includes plural light emitting layers that emit the light of different colors (for example, red, green, blue), since the light emitting layers emit the light of the plural colors, the colored layer54is not required. The filler layer46is disposed between the first substrate10and the second substrate48.

FIGS. 5A to 6Bare diagrams illustrating a method for manufacturing the organic electroluminescent display device according to the embodiment of the present invention.

As illustrated inFIG. 5A, the first substrate10is prepared. A circuit layer56is disposed on the first substrate10. The circuit layer56includes plural layers including the passivation film32and so on laminated over the first substrate10, as illustrated inFIGS. 3 and 4. The underlying layer34is formed on the circuit layer56. A conductive layer58is formed on the underlying layer34. The conductive layer58is formed with the inclusion of the connection portion16a. A mask layer60having a shape of the plurality of pixel electrodes16is formed on the conductive layer58. The mask layer60is patterned through photolithography.

As illustrated inFIG. 5B, the conductive layer58is patterned into the shape of the plurality of pixel electrodes16. In detail, a portion of the conductive layer58exposed from the mask layer60is removed by wet etching or the like. When the conductive layer58is formed of plural different layers, for example, made of indium tin oxide and silver, the conductive layer58is etched by respective different solutions.

As illustrated inFIG. 5C, the underlying layer34is so patterned as to overhang the ends of the plural pixel electrodes16. Ashing can be applied to patterning. The patterning is conducted by removing a portion of the insulating layer18exposed from the mask layer60. Alternatively, after the mask layer60has been removed, portions of the insulating layer18exposed from the plural pixel electrodes16may be removed with the plural pixel electrodes16as a mask.

As illustrated inFIG. 6A, the insulating layer18is formed to cover the plural pixel electrodes16and the underlying layer34. The insulating layer18is formed to extend between the pixel electrodes16adjacent to each other, and below the ends of the plural pixel electrodes16. The insulating layer18is formed to enter the hole34aof the underlying layer34. The insulating layer18can be formed to extend integrally to the upper and lower portions of the ends of the pixel electrodes16without conducting a complicated step such as half exposure. Also, when the insulating layer18is made of a liquid material, even if the viscosity of the material is high, the insulating layer18can be thinly formed on the ends of the pixel electrodes16.

As illustrated inFIG. 6B, the insulating layer18is patterned to expose at least center portions of the respective pixel electrodes16except for the ends of the pixel electrodes16. That is, the openings18aare formed in the insulating layer18.

Thereafter, as illustrated inFIGS. 3 and 4, the organic electroluminescent film38is formed with the inclusion of the common layer40that continuously covers exposed areas of the plural pixel electrodes16from the insulating layer18, and the insulating layer18. Then, the common electrode42is formed on the organic electroluminescent film38. Since the insulating layer18rests on the ends of the pixel electrodes16, short-circuiting between the ends of the pixel electrodes16and the common electrode42can be prevented.

Further, as illustrated inFIGS. 3 and 4, the second substrate and the color filter50are disposed. According to this embodiment, since the insulating layer18can be thinned on the pixel electrodes16, a thickness between the first substrate10and the second substrate48can be thinned.

FIG. 7is a partially enlarged plan view of an organic electroluminescent display device according to a modification1of the embodiment.FIG. 8is a cross-sectional view of the organic electroluminescent display device taken along a line VIII-VIII illustrated inFIG. 7. This example is different from the above embodiment (FIG. 4) in that a connection portion116ais bent toward a wiring layer130with the inclusion of the end of each of pixel electrodes116.

Therefore, the end of the pixel electrode116is also arranged in a hole134aof an underlying layer134. Since the connection portion116ais disposed on the end of the pixel electrode116, and separated from a center portion of the pixel electrode116, each opening118aof an insulating layer118for exposing the center portion of each pixel electrode116can be enlarged.

The hole134aof the underlying layer134is largely formed so as to extend from an area between the pixel electrodes116adjacent to each other to an end (connection portion116a) of one pixel electrode116. For that reason, the liquid material for forming the insulating layer118is liable to be filled. On the contrary, the underlying layer34illustrated inFIG. 4has the partition part36between the hole34aformed between the pixel electrodes16adjacent to each other, and the connection portion16aof one pixel electrode16. Therefore, the liquid material for forming the insulating layer18is accumulated on the connection portion16a.

The other details correspond to those described in the embodiments. For example, the wiring layer130is disposed below the plural pixel electrodes116in a first substrate110, and the connection portion116aof the pixel electrode116extends downward so as to be connected to the wiring layer130.

FIG. 9is a cross-sectional view of an organic electroluminescent display device according to a modification2of the embodiment. In this example, an insulating layer218has a concave portion262recessed in an upper surface thereof. The concave portion262is formed with the avoidance of above of the end of each pixel electrode216. That is, the concave portion262is formed above a hole234aof an underlying layer234. If the viscosity of a liquid material for forming the insulating layer218is set to be higher, the concave portion262is formed. A bottom surface of the concave portion262is located at a position lower than an upper surface of the pixel electrode216.

A common layer240is curved along the concave portion262. Since the insulating layer218is thin on the pixel electrodes216, a curvature of the common layer240in a swelling direction is small. On the other hand, the common layer240is curved downwardly along an inner surface of the concave portion262of the insulating layer218. A lower surface of the common layer240is located at a position lower than the upper surface of the pixel electrode216above the concave portion262of the insulating layer218. When the common layer240is curved downwardly, the waveguide of light can be prevented, and the color mixture caused by the entrance of the light from the adjacent pixels can be reduced.

A common electrode242is curved along a curvature of the common layer240. An organic electroluminescent film238and the common electrode242are covered and sealed with a sealing layer244. The sealing layer244has irregularities on a lower surface thereof along the curvature of the common electrode242.

FIG. 10is a cross-sectional view of an organic electroluminescent display device according to a modification3of the embodiment. In this example, a sealing layer344is formed of plural layers (an uppermost layer344A, an intermediate layer334B, and a lowermost layer344C). The lowermost layer344C of the sealing layer344is curved along the curvature of a common electrode342. The uppermost layer344A of the sealing layer344is flat on an upper surface thereof.

The present invention is not limited to the above embodiments, but can be variously modified. For example, the configurations described in the embodiments can be replaced with substantially the same configurations, configurations having the identical operational advantages, or configurations that can achieve the same purpose.