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Researchers Submit Patent Application, "Organic Light-Emitting Transistor and Organic Light Emitting Display Apparatus", for Approval

March 5, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Choi, Dae-Sung (Yongin-city, KR); Park, Won-Sang (Yongin-city, KR), filed on March 6, 2013, was made available online on February 20, 2014.

The patent's assignee is Samsung Display Co., Ltd.

News editors obtained the following quote from the background information supplied by the inventors: "The present disclosure relates to an organic light-emitting transistor and an organic light-emitting display apparatus.

"Display apparatuses using an organic light-emitting diode use a phenomenon in which light is emitted through a process in which electrons and holes form electron-hole pairs in a semiconductor or carriers excite to a higher energy state and then drop to a ground state, which is a stabilized state.

"However, unlike a liquid crystal display (LCD) apparatus, an organic light-emitting diode is driven in a current driving mode instead of a voltage driving mode. Thus, a separate device for controlling the organic light-emitting diode is required. At least two transistors including a switching transistor for selecting a pixel and a driving transistor for driving an organic light-emitting diode are required as devices for controlling the organic light-emitting diode.

"When a display apparatus includes a separate device for controlling an organic light-emitting diode, an area of a pixel is significantly reduced. Also, non-uniformity of a gradation is caused by dispersion of a threshold voltage Vth of a driving transistor by controlling the driving transistor in an analog manner, and this causes a problem to uniformity of the display apparatus. In addition, there is a need for a separate time for compensating for the threshold voltage Vth, and thus a timing problem is caused in an ultra definition (UD) three-dimensional (3D) display apparatus."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "An aspect of the present invention provides a display apparatus in which a single pixel may be formed to have a structure including a plurality of differential sub-pixels by using an organic light-emitting transistor having both a function as a transistor and a light-emitting function, and in which a gradation may be represented through a combination of on/off operations of sub-pixels.

"One aspect of the present invention provides an organic light-emitting transistor device including: a plurality of gate electrodes that have areas substantially different from one another and are arranged adjacent to one another; an insulation film formed over the gate electrodes; a plurality of source electrodes that have predetermined areas corresponding to the areas of the gate electrodes, respectively, and are formed over the insulation film and spaced apart from one another to face each other; a plurality of drain electrodes that have predetermined areas corresponding to the areas of the gate electrodes, respectively, and are formed over the insulation film and spaced apart from one another, each of the plurality of drain electrodes facing to one of the plurality of source electrodes; and an organic thin film layer disposed over the insulation film and drain electrodes and including an organic light-emitting material.

"The organic thin film layer may be disposed below the source electrodes and the drain electrodes.

"The organic thin film layer may include at least a portion formed in the same level as the source electrodes and the drain electrodes to fill gaps between the source electrodes and the drain electrodes.

"The organic thin film layer may include an emitting material layer and an active layer.

"The organic thin film layer may include an emitting material layer including an organic light-emitting material, and an electron transport layer and a hole transport layer, wherein the emitting material layer is disposed between the electron transport layer and the hole transport layer, wherein the electron transport layer or the hole transport layer is an active layer.

"Another aspect of the present invention provides an organic light-emitting transistor including: a plurality of gate electrodes that have areas substantially different from one another and are arranged adjacent to one another; an insulation film formed over the gate electrodes; a plurality of source electrodes disposed over the insulation film to be spaced apart from one another in parallel at substantially equal intervals and to cross the gate electrodes; a plurality of drain electrodes disposed over the insulation film, one of the drain electrodes being disposed between two of the source electrodes; and an organic thin film layer disposed over the insulation film, the organic thin film layer including an organic light-emitting material.

"The organic thin film layer may be disposed below the source electrodes and the drain electrodes.

"The organic thin film layer may include at least a portion formed in the same level as the source electrodes and the drain electrodes to fill gaps between the source electrodes and the drain electrodes.

"The organic thin film layer may include an emitting material layer and an active layer.

"The organic thin film layer may include an emitting material layer including an organic light-emitting material, and an electron transport layer and a hole transport layer, wherein the emitting material layer is disposed between the electron transport layer and the hole transport layer, wherein the electron transport layer or the hole transport layer is an active layer.

"Still another aspect of the present invention provides an organic light-emitting transistor including: a plurality of gate electrodes that have areas substantially different from one another and are arranged adjacent to one another; a first insulation film formed over the gate electrodes; an active layer formed over the first insulation film; a plurality of source electrodes disposed over the active layer to have a predetermined pattern; a second insulation film formed over the source electrode; an organic thin film layer including a first portion formed on the second insulating film and a second portion filling gaps between the source electrodes, the organic thin film layer including an organic light-emitting material; and a drain electrode formed over the organic thin film layer to be commonly formed over the gate electrodes.

"The organic thin film layer may include an emitting material layer including the organic light-emitting material, and an electron transport layer and a hole transport layer, wherein the emitting material layer is disposed between the electron transport layer and the hole transport layer.

"The source electrodes may include a plurality of electrode lines that are disposed over the active layer and spaced apart from one another at substantially equal intervals in parallel and to cross the gate electrodes.

"The source electrodes may be formed over the active layer in a honeycomb pattern or a lattice pattern.

"A further aspect of the present invention provides an organic light-emitting display apparatus including: a scan driver for supplying scan signals to a plurality of scan lines; a data driver for supplying data signals to a plurality of data lines; and a plurality of pixels formed near intersections between the scan lines and the data lines, wherein each of the pixels includes a plurality of sub-pixels by using an organic light-emitting transistor (OLET) device including a plurality of gate electrodes that have areas substantially different from one another and are arranged adjacent to one another, a plurality of source electrodes and a plurality of drain electrodes, and an organic thin film layer disposed over the gate electrode, the organic thin film layer including an organic light-emitting material, wherein the sub-pixels of the pixel selected by a scan signal are selectively turned-on/off by a data signal to represent a gradation.

"The gate electrodes of the pixel may be selectively turned-on by the data signal to thus selectively turn on the sub-pixels.

"When the number of gate electrodes is N (wherein, N is a natural number), the number of gradations to be represented may be 2.sup.(N).

"A value of the gradation may correspond to the sum of light-emitting areas of the turned-on sub-pixels.

"The source electrodes may have predetermined areas corresponding to the areas of the gate electrodes, respectively, and may be spaced apart from one another, wherein the drain electrodes have predetermined areas corresponding to areas of the gate electrodes, respectively, and are spaced apart from one another, wherein each of the drain electrodes faces one of the source electrodes.

"The source electrodes may be disposed over the gate electrodes and spaced apart from one another at substantially equal intervals in parallel and to cross the gate electrodes, and one of the drain electrodes may be disposed between two of the source electrodes.

"An active layer may be disposed over the gate electrodes, the source electrodes may be disposed over the active layer to be spaced apart from one another at substantially equal intervals in parallel and to cross the gate electrodes, and the drain electrodes may be commonly formed over the source electrodes across the gate electrodes.

"An active layer may be formed over the gate electrodes, the source electrodes may be formed in a honeycomb pattern or a lattice pattern, and the drain electrodes may be commonly formed over the source electrodes across the gate electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

"The above and other features and advantages of the present invention will become more apparent by describing in detail embodiments thereof with reference to the attached drawings in which:

"FIG. 1 is a schematic diagram showing a display apparatus according to an embodiment of the present invention;

"FIG. 2 is a schematic diagram showing a structure of a pixel shown in FIG. 1;

"FIGS. 3A to 3E are diagrams showing examples of representing a gradation, according to an embodiment of the present invention;

"FIG. 4 is a top plan view showing a structure of a pixel according to an embodiment of the present invention;

"FIGS. 5A and 5B are cross-sectional views taken along line A-A' and line B-B' of FIG. 4, respectively, according to an embodiment of the present invention;

"FIGS. 6A and 6B are schematic cross-sectional views showing a structure of an organic thin film layer according to an embodiment of the present invention;

"FIGS. 7A to 7C are cross-sectional views taken along line A-A' and line B-B' of FIG. 4, respectively, according to another embodiment of the present invention;

"FIG. 8 is a top plan view showing a structure of a pixel according to another embodiment of the present invention;

"FIGS. 9A and 9B are cross-sectional views taken along line C-C' and line E-E' of FIG. 8, respectively, according to an embodiment of the present invention;

"FIGS. 10A and 10B are cross-sectional views taken along line C-C' and line E-E' of FIG. 8, respectively, according to another embodiment of the present invention;

"FIG. 11 is a top plan view showing a structure of a pixel according to another embodiment of the present invention;

"FIGS. 12a and 12b are cross-sectional views taken along line F-F' and line H-H' of FIG. 11, respectively, according to an embodiment of the present invention;

"FIG. 13 is a diagram showing an electrode pattern of a source electrode, according to another embodiment of the present invention;

"FIG. 14 is a diagram showing an electrode pattern of a source electrode, according to another embodiment of the present invention."

For additional information on this patent application, see: Choi, Dae-Sung; Park, Won-Sang. Organic Light-Emitting Transistor and Organic Light Emitting Display Apparatus. Filed March 6, 2013 and posted February 20, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4305&p=87&f=G&l=50&d=PG01&S1=20140213.PD.&OS=PD/20140213&RS=PD/20140213

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

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Source: Electronics Newsweekly


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