Orthogonal processing of organic materials used in electronic and electrical devices
An orthogonal process for photolithographic patterning organic structures is disclosed. The disclosed process utilizes fluorinated solvents or supercritical CO 2 as the solvent so that the performance of the organic conductors and semiconductors would not be adversely affected by other aggressive solvent. One disclosed method may also utilize a fluorinated photoresist together with the HFE solvent, but other fluorinated solvents can be used. In one embodiment, the fluorinated photoresist is a resorcinarene, but various fluorinated polymer photoresists and fluorinated molecular glass photoresists can be used as well. For example, a copolymer perfluorodecyl methacrylate (FDMA) and 2-nitrobenzyl methacrylate (NBMA) is a suitable orthogonal fluorinated photoresist for use with fluorinated solvents and supercritical carbon dioxide in a photolithography process. The combination of the fluorinated photoresist and the fluorinated solvent provides a robust, orthogonal process that is yet to be achieved by methods or devices known in the art.
1. A method for patterning organic structures, the method comprising:
coating a substrate with a layer of fluorinated photoresist material, wherein the substrate comprises a first thin film of a first active organic electronic material;
selectively exposing portions of the layer of fluorinated photoresist material to radiation to form a first pattern of exposed fluorinated photoresist material and a second pattern of unexposed fluorinated photoresist material;
removing the second pattern of unexposed fluorinated photoresist material in a first fluorinated solvent thereby exposing portions of the substrate corresponding to the second pattern of unexposed fluorinated photoresist material;
depositing a second thin film of a second active organic electronic material over the first pattern of exposed fluorinated photoresist material and the substrate; and
removing the first pattern of exposed fluorinated photoresist material with a second fluorinated solvent that is the same as or different from the first fluorinated solvent, thereby removing the second thin film on the first pattern of exposed fluorinated photoresist material and leaving a pattern of the second thin film on the portions of the substrate corresponding to the second pattern of unexposed fluorinated photoresist material.
2. The method of claim 1 wherein at least one of the first and second active organic electronic material comprises a semiconducting polymer or a small molecule.
3. The method of claim 1 wherein the first fluorinated solvent comprises a hydrofluoroether.
4. The method of claim 1 wherein the second fluorinated solvent comprises a hydrofluoroether.
5. The method of claim 1 wherein both the first and second fluorinated solvents comprise a hydrofluoroether.
6. The method of claim 1 wherein the organic structure forms at least part of an organic thin film transistor, an organic light-emitting diode, an organic photovoltaic, an organic sensor, or a combination thereof.
7. The method of claim 1 wherein the layer of fluorinated photoresist material is coated from a composition comprising a fluorinated coating solvent.
8. The method of claim 7 wherein the fluorinated coating solvent comprises at least one hydrofluoroether.
9. The method of claim 1 wherein the fluorinated photoresist material comprises a photo-acid generator.
10. The method of claim 9 wherein the photo-acid generator is non-ionic.