and possible further research
screen-printing steps comprises using a screen made of at least one of metal, plastic, and cloth.
15. A The method of claim 1, wherein the second electrode includes indium tin oxide.
the improvement comprising: screen-printing at least one of the first and second electrodes; and screen-printing the organic material.
OLED displays are thinner, consume less power, offer a wider viewing angle, and have faster response time. They are particularly useful in devices with miniature display areas.
However, current fabrication methods of OLEDs are expensive, time consuming, and/or limited to certain applications. Such fabrication methods include high vacuum evaporation, spin casting, and high vacuum thermal deposition which are both expensive and time consuming. In addition, high vacuum thermal deposition is limited to fabrication of OLEDs with small molecules rather than polymers.
Polymer-based OLEDs have been fabricated using spin coating, a less expensive, but still time consuming method, such that patterning the OLEDs on a substrate in a single step is not possible. With larger displays, due to the multiple step patterning, uniformity of the OLEDs on the substrate becomes an issue. In addition, spin coating requires substrates having flat surfaces.
Recently, an ink-jet printing method has been developed to fabricate OLEDs using ink-jet printers which deposit the OLED materials on a substrate at a particular resolution similar to the method used by ink-jet printers to deposit ink on paper. However, such methods are currently limited to relatively low resolutions of 300 dpi, for example. This makes the technology unattractive in the fabrication of high definition OLED displays. Moreover, ink-jet printing fabrication is limited to flat surfaces and is time consuming because OLEDs are fabricated one at a time.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a fast, simple, and inexpensive method for fabricating OLEDs.
Another object of the present invention is to provide a method for fabricating OLEDs on various types and shapes of substrates.
Another object of the present invention is to provide a method for fabricating OLEDs which vary in size.
Another object of the present invention is to provide a method for fabricating an OLED display which has high definition/resolution.
These and other objects are accomplished by a novel method for fabricating OLEDs and OLED displays using screen-printing, in which layers of the OLEDs are deposited on the substrate through a screen having openings patterned to create OLEDs at a particular resolution on the substrate.
As such, the desired OLED pattern may be created easily by varying the spacing and width of the wires 3 to produce a desired HD display resolution. For example, given a specific display size, the screen 1 with the wires 3 spaced farther apart creates larger OLEDs and lower display resolution. Conversely, the screen 1 with the wires 3 spaced closer together creates smaller OLEDs and higher display resolution. Exemplary OLEDs fabricated by screen-printing may be at least as small as 20 µm×110 µm, easily patterned into a resolution of 2560 dpi in an HD display.
A p-type organic material which is capable of transporting holes is deposited onto the metallic layer 12 through the screen 1 . Prior to deposition, an organic material is doped with a p-type dopant to form the p-type organic material. Exemplary organic material includes polymers and/or small organic molecules capable of transporting charge and emitting light, such as polyphenylene vinylene (PPV). The p-type organic material forms p-type organic blocks 14 on the metallic layer 12 , as shown in FIG. 2C. The size and spacing of the p-type organic blocks 14 correspond to the size of the openings and the width of the wires, respectively, in the screen 1 .
The screen 1 is again repositioned and aligned above the n-type organic blocks 16 and metallic blocks 18 are formed, as shown in FIG. 2E. Exemplary metallic layers include indium tin oxide (ITO). The metallic layer 12 serves as a positive electrode and the metallic blocks 18 serve as negative electrodes. The size and spacing of the metallic blocks 18 are the same as that of the p-type and n-type organic blocks 14 and 16 .
… an ultrasonic bath of acetone, followed by isopropyl alcohol, followed by methanol, for example.
FIGS. 7A–7I illustrate a fifth embodiment of the fabrication of OLEDs in which red, green, and blue OLEDs are fabricated on the same substrate. Three different types of organic material are used to fabricate the OLEDs to emit red, green, and blue light. Exemplary organic material includes polymers and/or small organic molecules capable of transporting charge and emitting light, such as polyphenylene vinylene (PPV). The different dopants in the organic material determine the color of light emitted. The screen 2 of FIG. 5A is exemplary in this embodiment. FIG. 7A shows the deposition of the metallic layer 12 onto the substrate 10 as a continuous layer. The metallic layer 12 is then cleaned with an ultrasonic bath of acetone, followed by isopropyl alcohol, followed by methanol, for example. The screen 2 is positioned above the metallic layer 12 . In this embodiment, the opening 5 to the left and the solid region 7 with no openings to the right is indicative of half of the screen 2 shown in FIG. 5A.
Patent also describes how to get the various colors by dopants and screen size. That in itself is pretty big as the color green is known in less than complimentary terms.
Screen Printing is our niche
Metal, Plastic, and Cloth pretty much covers the medium
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids[citation needed] used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce costs. Monomers of plastic are either natural or synthetic organic compounds.
There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are the plastics that don't undergo chemical change in their composition when heated and can be moulded again and again; examples are polyethylene, polystyrene, polyvinyl chloride and polytetrafluoroethylene (PTFE).[3] Thermosets can melt and take shape once; after they have solidified, they stay solid.
Some things that may be worthy of further research
ITO (wherein the second electrode includes indium tin oxide)
PPV (small organic molecules capable of transporting charge and emitting light, such as polyphenylene vinylene)
Screen Printing 20um x 110um
HD display 2560dpi
Anyone know of specifics about agreement with FLOWID?
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