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Chemists Advance Clear Conductive Films

August 27, 2012
Efficient manufacture and optimized conductivity

Electron microscopy (cross-section, left, and facing view) shows an even distribution of indium titanium oxide nanocrystals essential for a highly conductive, transparent thin film. Credit: Sun Lab/Brown University

Chemistry graduate student Jonghun Lee is lead author of a paper demonstrating how a newly developed chemical solution is used to create a thin, conductive film that reports the best transparency and conductivity performance to date. A conductive overlay in a touch-screen display or solar panel must be clear, inexpensive and easy to manufacture. Engineers use transparent thin films of indium tin oxide (ITO) for this purpose. In the new study, Lee, along with Shouheng Sun, professor of chemistry, and other researchers at Brown and ATMI Inc. show superior transparency and conductivity performance for an ITO made using a chemical solution, which is potentially the easy, low-cost method manufacturers desire.

The group made conductive ITO films 146 billionths of a meter thick that allowed 93 percent of light to pass through, a transparency comparable to the glass plates they were deposited on. The team also made their films on top of bendable polyimide, showing that it could potentially be useful for making flexible display technologies. In several experiments they showed that by varying the thickness and the tin content (between 5 and 10 percent was best) they could vary the transparency and resistance to find the best combination.

Learn more about conductive films in David Orientstein's article.