Invented by Sang-Hun Oh, Samsung Display Co Ltd
The Samsung Display Co Ltd invention works as followsThe disclosure is “An organic luminescence display and a manufacturing method for the same that are configured to prevent IR drops of a second electrolyte by forming an auxiliary electroluminescence line in an electroluminescence device.” Display device also prevents pixel shrinkage due to deterioration in an organic electroluminescent film caused by transfer of gases. This out-gassing can be prevented by reducing the contact area of the auxiliary electroluminescent line with the second electrode.
Background for Organic Electroluminescence Display Device having auxiliary electrode Line and Method of Manufacturing the Same
This application claims priority to Korean Patent Application No. The Korean Intellectual Property Office filed 10-2004-98878 on Nov. 29th, 2004. Its disclosure is incorporated in full by reference.
The present invention is a general description of organic electroluminescence displays and manufacturing methods, and it is more specifically a display device that prevents pixel shrinkage caused by degradation of an organic layer.
The organic electroluminescence device (OLED display) has many desirable features, including spontaneous emission, wide viewing angles, rapid response, small thicknesses, low production costs, and high contrast. The organic electroluminescence device has received a lot of attention as the next-generation flat display device.
An example organic electroluminescence device comprises an organic electroluminescent film interposed between an anode and cathode electrode. In an excited state, electrons and holes from the anode electrode and cathode are combined to form electron-hole pair. These excited electron-hole pair can be referred as excitons. The energy difference between excited and ground states of the excitons is emitted when the excitons return back to the ground state.
More precisely, each unit pixel in the active matrix type of organic electroluminescence displays device includes a transistor for switching, a transistor for driving, a capacitance, and an EL element such as a diode. As a power source for the driving transistor and capacitor, a voltage supply line (Vdd) is provided. The voltage supply Vdd controls current flow through the driving transistor and to the EL element. A second electrode is also provided with an auxiliary voltage supply line. The auxiliary electrode provides a current through a potential differential between the source/drain and second electrodes.
FIG. FIG. 1 shows a cross-sectional view of a typical active matrix type organic luminescence display device. Referring to FIG. The conventional active matrix type of organic electroluminescence displays 10 consists of a substrate 100 with panel and wire regions (A and B) and a layer of buffer 105. In the panel region A, a semiconductor layer 110 with source/drain region 110 c and 11 a, and a channel area 110 b is disposed over the buffer layer 105. The patterning of the channel region 110 and the source/drain areas 110 c and a is one embodiment.
The display device 10 also comprises a gate-insulating layer (120) disposed on top of the semiconductor layer 110 and a channel electrode 110 b corresponding to it formed in the panel area A. On the gate electrode 130, an interlayer insulating film 140 is formed over the surface of the substrate. After formation of the interlayer layer 140, the source/drain region 110 c and the source/drain region 110 a are connected through contact holes (141) formed in the interlayer layer 140 in panel area A. The gate electrode 130 and the source/drain electrodes 145 together form a thin-film transistor (TFT).
In the wire region B, “a first conductive pattern” 147 is formed. This first conductive design 147 is made of the same material that the source/drain electrodes 145 are made from. The first conductive line 147 is formed by the first conductive pattern. On the source/drain electrodes 145, the first conductive layer 147 and substantially the entire substrate 100, an insulating 150 layer is then formed, for example, a planarization or passivation layer. The insulating 150 layer formed on the upper part of the first conductive patterns 147 in wire region B, is then removed, by way of a lithography procedure, for example.
A via-hole 155 is formed in the insulating layers 150 of the panel region A, to expose one source/drain electrode 145.” “A first electrode 170 formed by a patterning procedure is positioned to contact the source/drain electrodes 145 through via hole 155 and extend to insulating layers 150.
Following the formation of the first electrolyte 170, and to the exclusion the wire region B is formed a pixel-defining layer 175 with an opening 178 on the first electrode 150 and the insulating layers. On the first electrode exposed by the opening of the panel region A, a layer organic 180 is then formed, which includes at least one organic electroluminescent. This organic layer 180 can be created, for instance, by patterning. On the organic layer 180, a second electrode 190 may be formed over the substantially entire surface of substrate 100. The second electrode 190 of the wire region B in the substrate 100 is then electrically connected to first conductive pattern.
The first conductive patterns 147 of some organic electroluminescence displays may comprise the same material that is used for the source/drain 145 electrodes in panel region A. Also, the line width of first conductive patterns 147 can be quite large. The first conductive patterns 147 are made of molybdenum, tungsten and molybdenum-tungsten. These materials have a greater heat capacity than the silicon nitride layer (SiNx). The “heat capacity” is the amount of heat energy required to change a substance’s temperature by one degree. The heat capacity of a substance is defined as the amount of energy needed to raise its temperature one degree. It has units per degree. Due to differences in heat capacities between the first conductor pattern 147, and the silicon-nitride layers, the first conductor pattern 147 is unable to transfer heat effectively to the silicon-nitride layers. Reflow cannot be performed effectively between the different panel regions in the curing of the organic layers. The curing process has different effects on each panel region of a display. This causes the organic layer thickness to vary between panel regions. Gases remaining in organic layers can also cause pixel shrinkage. The out-gassing of organic layers or the gases that remain in the layer can cause the organic electroluminescent display to deteriorate.
Furthermore a small width of the first conductor pattern 147 can cause IR drops at the second electrode. The IR effect is caused by the wire resistance, and current from the power grid and ground grid. A voltage drop can occur if the wire resistance or cell current is higher than expected. It results in poor performance as well as increased noise susceptibility.
In order solve the aforementioned issues, embodiments include an organic luminescence display device, and a manufacturing method thereof, wherein IR drops of a second electroluminescence device are prevented by forming an auxiliary electroluminescence line. The auxiliary line is made up of a number of patterns or trenches that reduce the contact area between it and the second electrode. This reduced contact area improves heat transfer when an organic layer is cured in the display device. This improved heat transfer leads to a uniform organic layer that allows for the removal of any gases in the organic layer. This prevents deterioration due to the out-gassing into the organic electroluminescent layers. This prevents pixel shrinkage caused by deterioration in the organic electroluminescent layers.
According to a “first aspect” of the invention an organic electroluminescence device comprises a board with a panel and wire regions, and a thin-film transistor in the panel area of the board, wherein said thin-film transistor is composed of a semiconductor, a gate, and source/drain. Display device also comprises a plurality first conductive pattern formed in wire region of substrate, an insulating layers formed over the first conductive pattern to expose at the least the first patterns, and first electrode formed through via hole in the insulating material in contact with the one of the source/drain electrodes. Display device further comprises a plurality second conductive pattern formed on first conductive patterns of the wire region. An organic layer is formed using a patterning technique on the first electrode of the panel region. The organic layer includes at least one organic luminescent layer. A second electrode is formed over the entire surface area of the substrate on the second electrode.
In some embodiments, first and second conductive lines are electrically connected with the second electrode in order to form an auxiliary electrode. The first conductive pattern may be made of the same material that is used for the source/drain and second conductive pattern may be made of the same material that is used for the first electrode.
According to a second embodiment of the invention an organic electroluminescence device comprises a substrate with a panel and wire region. The thin film transistor is formed in the panel area of the substrate and comprises a semiconductor, a gate and drain electrodes. Display device also comprises a first conductor pattern formed in a wire region of substrate, which has a trench. An insulating film is formed over the first conductor pattern to expose the trench and at least the first conductor pattern. A first electrode is formed so that it contacts one of the source/drain electrodes through a hole in the insulating film. Display device further comprises an organic coating formed by a patterning technique on the first electrode of the panel region, the organic coating comprising at least an electroluminescent organic layer. A second electrode is formed over the organic coat on substantially the entire substrate surface. In the second aspect, the first electrode may be electrically coupled to the first conductive line to form an auxiliary electroluminescent line. The first conductive pattern can also have a trench made of the same material used for the source/drain electrodes.
According to a third feature of the invention an organic electroluminescence device includes a substrate with a panel and wire regions, and a thin-film transistor in the panel area of the substrate. The thin-film transistor comprises a source/drain and gate electrodes, as well as a semiconductor layer. Display device also comprises a plurality first conductive pattern formed in the wire area of the substrate. An insulating sheet is formed to expose upper portions of these first conductive pattern, a via-hole in the insulating sheet, and a first electrode contacting one of the source/drain electrodes through the via hole. Display device further comprises an organic coating formed by a patterning technique on the first electrode of the panel region, the organic coating comprising at least a 1st organic electroluminescent film, and a 2nd electrode formed over the entire substrate surface. In this third embodiment, the first electrode and the second electrode may be electrically coupled to form an auxiliary line. The first conductive pattern may also be made of the same material that is used for the gate electrode. The second conductive pattern may also be made of the same material that is used for the first electrode.
According to the fourth aspect of the present invention, an electroluminescence organic display device is composed of a substrate with a panel and wire regions, and a thin-film transistor in the panel area of the substrate. The thin-film transistor consists of a semiconductor, a gate, and source/drain, electrodes. Display device also includes a first conductive layer in the wire area of the substrate with a trench. An interlayer insulating film is then formed over the first pattern to reveal at least a portion of it. Finally, the display device has an insulating sheet. The insulating sheet is formed onto the source/drain electrodes and removed from the upper portion using a lithography procedure. Display device further comprises a first conductive pattern formed in the wire region of the substrate and having a trench, an interlayer insulating film formed over the first conductive pattern to expose at least an upper portion of the first conductive pattern, and an insulating sheet, wherein the insulated layer is formed on one of the source/drain electrodes through a hole formed in a via layer in the insulating material, a layer of organic material formed using a patterned process on the first conductive layer In this fourth embodiment, the first conductive patterns may be electrically coupled to the second electrode to form an auxiliary line. The first conductive pattern can also have a trench made of the same material that is used for the gate electrode.
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