1. Field of the Invention
The present invention generally relates to an organic electroluminescence device and a method of forming the same. More particularly, the present invention relates to a passive matrix organic electroluminescence device and a method of forming the same.
2. Description of Related Art
Organic electroluminescent devices are spontaneous emission devices that emit light by electrically exciting fluorescent organic compounds. The organic electroluminescent devices are expected to be applied to next generation display devices that can overcome shortcomings of liquid crystal display devices, with characteristics including a low driving voltage, enabling the production of thin and small display panels having a wide viewing angle, and a high response speed.
Generally, a passive matrix organic electroluminescence device comprises first strip electrodes, second strip electrodes cross the first electrodes and an organic emitting layer sandwiched between the first and second strip electrodes. The first and the second strip electrodes are composed of indium-tin oxide (ITO) so that auxiliary electrodes for electrically connecting with the first/second electrodes and driving circuits are required for improving electrically contact between the first/second electrodes and the driving circuits.
Conventionally, the auxiliary electrodes are made of a multiple layer of Cr/Al/Cr or a single layer of silver (Ag). However, if the auxiliary electrodes are made of the multiple layer of Cr/Al/Cr, more sputtering chambers and etching chambers are required because two metals (Cr and Al) are used. If the auxiliary electrodes are made of the single layer of Ag, the silver is easy oxidized so as to worsen the auxiliary electrode resistance.
Accordingly, the present invention is directed to an organic electroluminescence device having low resistance auxiliary electrodes.
The present invention is directed to a method of forming an organic electroluminescence device capable of simplifying manufacturing process and preventing the auxiliary electrodes from oxidizing.
According to an embodiment of the present invention, an organic electroluminescence device comprising a plurality of first electrodes, a plurality of first auxiliary electrodes, a plurality of second auxiliary electrodes, a plurality of organic emitting patterns and a plurality of second electrodes is provided. The first electrodes are arranged on a substrate. The first auxiliary electrodes are disposed on at least one edge of the substrate, wherein each first auxiliary electrode is electrically connected with each first electrode. The second auxiliary electrodes are disposed on another edge of the substrate, wherein the first auxiliary electrodes and the second auxiliary electrodes are constituted of a double layer of an aluminium-neodymium (Al—Nd) alloy layer and an aluminium-neodymium nitride layer. The organic emitting patterns are arranged over the first electrodes. The second electrodes are arranged over the organic emitting patterns, wherein each second electrode is electrically connected to each second auxiliary electrode.
According to an embodiment of the present invention, the aluminium-neodymium alloy layer has a thickness in a range of 100˜400 nm. The aluminium-neodymium nitride layer has a thickness in a range of 5˜100 nm.
According to an embodiment of the present invention, the device further comprises a pixel defining layer disposed over the first electrodes and the pixel defining layer exposes a portion of the first electrodes.
According to an embodiment of the present invention, the device further comprises a separating layer disposed on the pixel defining layer.
According to another embodiment of the present invention, an organic electroluminescence device comprising a plurality of first electrodes, a plurality of first auxiliary electrodes, a plurality of second auxiliary electrodes, a covering layer, a plurality of organic emitting patterns and a plurality of second electrodes is provided. The first electrodes are arranged on a substrate. The first auxiliary electrodes are disposed on at least one edge of the substrate, wherein each first auxiliary electrode is electrically connected with each first electrode. The second auxiliary electrodes are disposed on another edge of the substrate, wherein the first auxiliary electrodes and the second auxiliary electrodes are constituted of a silver layer or a silver alloy layer. The covering layer is disposed on the edges of the substrate to cover a portion of the first and second auxiliary electrodes. The organic emitting patterns are arranged over the first electrodes. The second electrodes are arranged over the organic emitting patterns, wherein each second electrode is electrically connected to each second auxiliary electrode.
According to an embodiment of the present invention, the silver or silver alloy layer has a thickness in a range of 200˜500 nm. The covering layer has a thickness in a range of 500˜4000 nm.
According to another embodiment of the present invention, a method of forming an organic electroluminescence device is described. First, a plurality of first electrodes is formed on a substrate. A plurality of first auxiliary electrodes is formed on at least one edge of the substrate and a plurality of second auxiliary electrodes is formed on another edge of the substrate, wherein each first auxiliary electrode is electrically connected to each first electrode, and the first auxiliary electrodes and the second auxiliary electrodes are constituted of a double layer of an aluminium-neodymium (Al—Nd) alloy layer and an aluminium-neodymium nitride layer. A plurality of organic emitting patterns is formed over the first electrodes. A plurality of second electrodes is formed over the organic emitting patterns, wherein each second electrode is electrically connected to each second auxiliary electrode.
According to an embodiment of the present invention, the step of forming the first auxiliary electrodes and the second auxiliary electrodes comprises: forming a first aluminium-neodymium alloy layer; forming a second aluminium-neodymium alloy layer on the first aluminium-neodymium alloy layer; performing a nitridation step for the second aluminium-neodymium alloy layer to form an aluminium-neodymium nitride layer; and patterning the aluminium-neodymium nitride layer and the first aluminium-neodymium alloy layer so as to form the first and second auxiliary electrodes.
According to an embodiment of the present invention, the method further comprises forming a pixel defining layer over the first electrodes before forming the organic emitting patterns.
According to an embodiment of the present invention, the method further comprises forming a separating layer on the pixel defining layer before forming the second electrodes.
According to another embodiment of the present invention, a method of forming an organic electroluminescence device is described. First, a plurality of first electrodes is formed on a substrate. A plurality of first auxiliary electrodes is formed on at least one edge of the substrate and a plurality of second auxiliary electrodes is formed on another edge of the substrate, wherein each first auxiliary electrode is electrically connected to each first electrode, and the first auxiliary electrodes and the second auxiliary electrodes are constituted of a silver layer or a silver alloy layer. A covering layer is formed on the edges of the substrate to cover a portion of the first and second auxiliary electrodes. A plurality of organic emitting patterns is formed over the first electrodes. A plurality of second electrodes is formed over the organic emitting patterns, wherein each second electrode is electrically connected to each second auxiliary electrode.
According to an embodiment of the present invention, the method further comprises forming a pixel defining layer over the first electrodes before forming the organic emitting patterns. In addition, the covering layer can be formed when forming the pixel defining layer.
According to an embodiment of the present invention, the method further comprises forming a separating layer on the pixel defining layer before forming the second electrodes. In addition, the covering layer is formed when forming the separating layer.
In the present invention, the first and second auxiliary electrodes are constituted of a double layer of an aluminium-neodymium (Al—Nd) alloy layer and an aluminium-neodymium nitride layer. Comparing with the conventional method using Cr/Al/Cr auxiliary electrodes, the method of the present invention only needs one target (Al—Nd alloy target) and one etching recipe to form the first and second auxiliary electrodes so that the process complexity and the process time are reduced.
If the first and second auxiliary electrodes are constituted of silver (Ag) or silver alloy having lower resistance, a covering layer is further formed over the first and second auxiliary electrodes to protect the first and second auxiliary electrodes from oxidizing. In addition, the covering layer can be formed when defining the pixel defining layer or the separating layer so that the number of photo-mask is not increased.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
Next, a plurality of first auxiliary electrodes 104 is formed on at least one edge of the substrate 100, and a plurality of second auxiliary electrodes 106 is formed on another edge of the substrate 100. Each first auxiliary electrode 104 is electrically connected with each first electrode 102. In an embodiment, the first and second auxiliary electrodes 104, 106 are formed at the same time. In addition, the first auxiliary electrodes 104 can be formed on the first electrodes 102 so that each first auxiliary electrode 104 can be electrically connected with each first electrode 102. In another embodiment, when forming the first electrodes 102, a plurality of conductive patterns 102a may also be formed on the edge of the substrate 100 in which the second auxiliary electrodes 106 are sequentially formed on the conductive patterns 102a.
In particular, the first auxiliary electrodes 104 and the second auxiliary electrodes 106 are constituted of a double layer of an aluminium-neodymium (Al—Nd) alloy layer and an aluminium-neodymium nitride layer (not shown). In details, the first auxiliary electrodes 104 and the second auxiliary electrodes 106 are constituted of a lower layer of an aluminium-neodymium alloy and an upper layer of aluminium-neodymium nitride. In an embodiment, the aluminium-neodymium alloy layer has a thickness in a range of 100˜400 nm. The aluminium-neodymium nitride layer has a thickness in a range of 5˜100 nm. The first auxiliary electrodes 104 and the second auxiliary electrodes 106 are formed by the steps of forming a first aluminium-neodymium alloy layer over the substrate by sputtering process; forming a second aluminium-neodymium alloy layer over the first aluminium-neodymium alloy layer by sputtering process; performing a nitridation step for the second aluminium-neodymium alloy layer to form an aluminium-neodymium nitride layer; and patterning the aluminium-neodymium nitride layer and the first aluminium-neodymium alloy layer to form the first and second auxiliary electrodes 104, 106. In an embodiment, the nitridation step is carried out by flowing 100˜150 sccm Ar gas and 1˜10 sccm N2 gas into the sputtering process chamber.
As shown in
Thereafter, as shown in
In a preferred embodiment, before forming the organic emitting patterns 108 (shown in
In the first embodiment of the present invention, the first and second auxiliary electrodes 104, 106 are constituted of a double layer of an aluminium-neodymium alloy layer and an aluminium-neodymium nitride layer. Comparing with the conventional method using Cr/Al/Cr auxiliary electrodes, the present invention only uses one target (Al—Nd alloy target) and one etching recipe to form the first and second auxiliary electrodes 104, 106 so that the process complexity and the process time are reduced.
In the second embodiment of the present invention, the method of forming the organic electroluminescence device is similar to the first embodiment except the first and second auxiliary electrodes are constituted of a silver (Ag) layer or a silver alloy layer, and a covering layer is further formed over the first and second auxiliary electrodes. As shown in
In the second embodiment, a pixel defining layer 112 and a separating layer 114 may also be formed over the substrate 100 (as shown in
In another embodiment, as shown in
In the second embodiment of the present invention, the first and second auxiliary electrodes are constituted of a silver (Ag) layer or a silver alloy layer having lower resistance, and a covering layer is further formed over the first and second auxiliary electrodes to protect the first and second auxiliary electrodes from oxidizing. In addition, the covering layer can be formed when defining the pixel defining layer or the separating layer so that the number of photo-mask is not increased.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.