News Column

Patent Application Titled "Organic Light Emitting Diode Display Device and Method of Fabricating the Same" Published Online

July 23, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors BAEK, Heume-Il (Gyeonggi-do, KR); LEE, Ji-Heun (Seoul, KR), filed on August 22, 2013, was made available online on July 10, 2014.

The assignee for this patent application is LG Display Co., Ltd.

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to an organic light emitting diode (OLED) display device, and more particularly, to an OLED display device including four color emitting layers and method of fabricating the OLED display device.

"An OLED display device of new flat panel display devices is a self-emitting type. Since the OLED display device does not require a backlight, which is required for a liquid crystal display device, the OLED device has a thin profile and light weight.

"Particularly, various colors, e.g., red, green, blue, cyan, light-blue, and so on, can be displayed using an organic material. The red and green phosphorescent materials having excellent efficiency and lifetime are used, while the deep-blue fluorescent material having similar color property and lifetime as the red and green phosphorescent materials are used. However, the deep-blue fluorescent material has low efficiency such that there is a disadvantage in power consumption.

"FIG. 1 is a graph of simulation data for showing power consumption in an OLED display device using a red phosphorescent material PH_R, a green fluorescent material FL_G, a green phosphorescent material PH_G, a blue phosphorescent material PH_B1 and a blue fluorescent material FL_B2.

"FIG. 1 shows power consumption of the OLED display device, which uses the red phosphorescent material PH_R, the green phosphorescent material PH_G and the blue phosphorescent material PH_B1, is decreased by about 45% in comparison to the OLED, which uses the red phosphorescent material PH_R, the green phosphorescent material PH_G and the blue fluorescent material FL_B2.

"FIG. 2 is a schematic plane view of the sub-pixel arrangement in the related art OLED device.

"In FIG. 2, one pixel 100a includes red, green and blue sub-pixels R, G and B. On the other hand, another pixel 100b includes the red sub-pixel R, the green sub-pixel G, a light-blue sub-pixel B1 of a phosphorescent material and a deep-blue sub-pixel B2 of the fluorescent material to prevent a problem of power consumption increase resulted from the fluorescent material.

"In addition, to display images, the light-blue material is used above 70%, and the deep-blue material is used below 30%. The light-blue image is displayed using the phosphorescent material, while the deep-blue is displayed using the fluorescent material. Accordingly, the four emitting materials and four deposition processes are required to fabricate the OLED display device having the pixel 100b.

"Referring to FIG. 3, which is a schematic cross-sectional view of the related art OLED display device including red, green, first blue and second blue sub-pixels, a fabricating process of the OLED display device is explained.

"As shown in FIG. 3, the OLED display device includes an organic emitting cell. The organic emitting cell includes a first electrode 106 connected to a thin film transistor (TFT) T, which is formed on a substrate 101, a hole injecting layer 107, a hole transporting layer 108, an emitting layer 109, an electron transporting layer 110, an electron injecting layer 111, and a second electrode 112. The hole injecting layer 107, the hole transporting layer 108, the emitting layer 109, the electron transporting layer 110, the electron injecting layer 111, and the second electrode 112 are stacked on the first electrode 106.

"Particularly, after forming the TFT T on the substrate 101, the first electrode 106, the hole injecting layer 107 and the hole transporting layer 108 are formed. Next, the red emitting layer 109R, the green emitting layer 109G, the light-blue emitting layer 109B1 and the deep-blue emitting layer 109B2 are formed in the red sub-pixel R, the green sub-pixel G, the first blue sub-pixel B1 and the second blue sub-pixel B2. To form the four-colored pixel structure, a step of forming the light-blue emitting layer 109B1 or the deep-blue emitting layer 109B2 is further required.

"Namely, since the OLED display device having the four-colored pixel structure includes the red, green, first blue and second blue sub-pixels R, G, B1 and B2, production costs and fabricating steps are increased in comparison to the OLED display device having the three-colored pixel structure. In addition, since the fluorescent material is used for displaying the deep-blue, there are still disadvantages in power consumption."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "Accordingly, the present invention is directed to an OLED display device and a method of fabricating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

"Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. These and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

"In accordance with the present invention, as embodied and broadly described herein, OLED display device includes a substrate; pixel regions defined by gate lines and data lines formed on the substrate, each pixel region including red, green, first blue and second blue sub-pixels; a thin film transistor in each pixel region; a first electrode electrically connected to a drain electrode of the thin film transistor; an insulating layer exposing the first electrode; a hole injecting layer and a hole transporting layer sequentially stacked on the first electrode; red, green and blue emitting layer on the hole transporting layer, the red and green emitting layers respectively being in the red and green sub-pixels, and the blue emitting layer being in the first and second blue sub-pixels; an electron transporting layer and an electron injecting layer sequentially stacked on the red, green and blue emitting layers; and a second electrode on the insulating layer and the electron injecting layer, wherein the first electrode in the second blue sub-pixel has a multi-layered structure of the first electrode layer and at least one metal layer.

"Preferably, the first blue sub-pixel may display a light-blue color, and the second blue sub-pixel may display a deep-blue color.

"Preferably, the multi-layered structure may be a double-layered structure of the first electrode layer and a first metal layer under the first electrode layer, and the first metal layer includes Ag or Ag alloy, and wherein the first electrode layer includes ITO or IZO or other transparent conductive materials.

"Preferably, the multi-layered structure may be a triple-layered structure of the first electrode layer, a first metal layer on the first electrode layer and a second metal layer on the first metal layer, and each of the first electrode layer and the second metal layer includes ITO or IZO or other transparent conductive materials, and wherein the first metal layer includes Ag or Ag alloy.

"Preferably, the first electrode layer may have a thickness more than 0 angstrom and less than about 300 angstroms, and the first metal layer may have a thickness of about 100 to 200 angstroms.

"Preferably, the first electrode layer may have a thickness more than 0 angstrom and less than about 300 angstroms, and the first metal layer may have a thickness of about 100 to 200 angstroms, and wherein the second metal layer has a thickness more than 0 angstrom and less than about 100 angstroms.

"Preferably, the blue emitting layer in the first and second blue sub-pixels, may include the same blue phosphorescent organic material.

"Preferably, the second electrode may include Al.

"A substrate for an organic light emitting diode display device, comprising: a substrate; a plurality of pixel regions defined by a plurality of gate lines and a plurality of data lines formed on the substrate, each pixel region including red, green, first blue and second blue sub-pixels; a thin film transistor in each pixel region; a first electrode electrically connected to a drain electrode of the thin film transistor; an insulating layer exposing the first electrode; a hole injecting layer and a hole transporting layer sequentially stacked on the first electrode; red, green and blue emitting layer on the hole transporting layer, the red emitting layer being in the red sub-pixel, the green emitting layer being in the green sub-pixel, and the blue emitting layer being in the first and second blue sub-pixels; an electron transporting layer and an electron injecting layer sequentially stacked on the red, green and blue emitting layers; and a second electrode on the insulating layer and the electron injecting layer, wherein the first electrode in the second blue sub-pixel has a multi-layered structure of the first electrode layer and at least one metal layer.

"Preferably, the multi-layered structure may be a double-layered structure of the first electrode layer and a first metal layer under the first electrode layer, or a triple-layered structure of the first electrode layer, a first metal layer on the first electrode layer and a second metal layer on the first metal layer.

"Preferably, the blue emitting layer in the first and second blue sub-pixels may include the same blue phosphorescent organic material.

"In the another aspect, a method of fabricating an organic light emitting diode display device includes forming a plurality of gate lines and a plurality of data lines to define a plurality of pixel regions, each pixel region including red, green, first blue and second blue sub-pixels; forming a thin film transistor in each pixel region, wherein the first electrode in the second blue sub-pixel has a multi-layered structure of the first electrode layer and at least one metal layer; forming a first electrode electrically connected to a drain electrode of the thin film transistor; forming an insulating layer exposing the first electrode; sequentially forming a hole injecting layer and a hole transporting layer stacked on the first electrode; forming red, green and blue emitting layer on the hole transporting layer, the red emitting layer being in the red sub-pixel, the green emitting layer being in the green sub-pixel, and the blue emitting layer being in the first and second blue sub-pixels; sequentially forming an electron transporting layer and an electron injecting layer sequentially stacked on the red, green and blue emitting layers; and forming a second electrode on the insulating layer and the electron injecting layer.

"Preferably, the first blue sub-pixel may display a light-blue color, and the second blue sub-pixel may display a deep-blue color.

"Preferably, the multi-layered structure may be a double-layered structure of the first electrode layer and a first metal layer under the first electrode layer, and the first metal layer may include Ag or Ag alloy, and wherein the first electrode layer may include ITO or IZO or other transparent conductive materials.

"Preferably, the multi-layered structure may be a triple-layered structure of the first electrode layer, a first metal layer on the first electrode layer and a second metal layer on the first metal layer, and each of the first electrode layer and the second metal layer includes ITO or IZO or other transparent conductive materials, and wherein the first metal layer includes Ag or Ag alloy.

"Preferably, the first electrode layer may have a thickness more than 0 angstrom and less than about 300 angstroms, and the first metal layer may have a thickness of about 100 to 200 angstroms.

"Preferably, the first electrode layer may have a thickness more than 0 angstrom and less than about 300 angstroms, and the first metal layer may have a thickness of about 100 to 200 angstroms, and wherein the second metal layer may have a thickness more than 0 angstrom and less than about 100 angstroms.

"Preferably, the blue emitting layer in the first and second blue sub-pixels may include the same blue phosphorescent organic material.

"Preferably, the second electrode may include Al.

"It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

"The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

"FIG. 1 shows power consumption according to materials of an emitting material for the OLED display device.

"FIG. 2 is a schematic plane view of the sub-pixel arrangement in the related art OLED device.

"FIG. 3 is a schematic cross-sectional view of the related art OLED display device including red, green, first blue and second blue sub-pixels.

"FIG. 4 is a schematic cross-sectional view of an OLED display device according to an exemplary embodiment of the present invention.

"FIGS. 5A to 5J are cross-sectional views showing fabricating processes of an OLED display device according to an exemplary embodiment of the present invention.

"FIG. 6 is a schematic cross-sectional view of an OLED display device according to another exemplary embodiment of the present invention.

"FIG. 7 is a color-coordinate of first and second blue colors in an OLED display device according to an exemplary embodiment of the present invention."

For more information, see this patent application: BAEK, Heume-Il; LEE, Ji-Heun. Organic Light Emitting Diode Display Device and Method of Fabricating the Same. Filed August 22, 2013 and posted July 10, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=6458&p=130&f=G&l=50&d=PG01&S1=20140703.PD.&OS=PD/20140703&RS=PD/20140703

Keywords for this news article include: Electronics, LG Display Co. Ltd., Light-emitting Diode.

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Source: Electronics Newsweekly


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