Princeton Scientists Use Acid to Restore Conductivity in Plastics

Breakthrough is promising to electronics, solar, and medical industries

Conductors of electricity on solar panels ideally must be transparent and highly conductive. One solution currently used is indium tin oxide (ITO); however, ITO is very expensive. Plastic, on the other hand, is cheap, transparent and flexible; however, it does not conduct well. Princeton University researchers believe that they have discovered how to fix that problem.

The researchers at Princeton theorized that the molded polymer was fixed in a rigid structure that blocked the natural conductivity of its free form in solution. They used an acid treatment to alter the polymer, restoring much of its conductivity.

The result was a transistor with polymer electrodes, printed on a surface. The manufacturing process used was similar to how an inkjet printer works. That alone, is a big deal says associate professor of chemical engineering Yueh-Lin Loo, who led the research. She states, "Being able to essentially paint on electronics is a big deal. You could distribute the plastics in cartridges the way printer ink is sold, and you wouldn’t need exotic machines to print the patterns."

The material could also cut costs of deploying solar. States Yueh-Lin, "The cost of indium tin oxide is skyrocketing. To bring down the costs of plastic solar cells, we need to find a replacement for ITO. Our conducting plastics allow sunlight to pass through them, making them a viable alternative."

The work also has other practical applications. The acid treatment typically yields a color change. Ear infections in children tend to produce Nitric Oxide, which turns plastics from yellow to green. The team proposed a prototype device to check for these hard-to-detect infections by monitoring changes in a plastic. That could help battle reoccurring childhood ear infections, a major cause of hearing loss.

The new work is published in the March 8 edition of the prestigious journal Proceedings of the National Academy of Sciences.

It was funded by the National Science Foundation and other private foundations. Other members of Yueh-Lin's team working on the project included, Joung Eun Yoo, who received her doctorate in chemical engineering from the University of Texas-Austin in 2009 with Loo as her adviser; Kimberly Baldwin, a high school student who spent a summer in Loo's lab; Jacob Tarver, a Princeton chemical engineering graduate student; Enrique Gomez of Pennsylvania State University; Kwang Seok Lee and Yangming Sun of the University of Texas-Austin; Andres Garcia and Thuc-Quyen Nguyen of the University of California-Santa Barbara; and Hong Meng of DuPont Central Research and Development.