Research at the University of Michigan in Ann Arbor suggests that paint-on plastic electronics, made possible by smarter semiconducting polymers, could someday be used for making electronics of all sizes such as LED displays or light-absorbing coatings for solar cells.
“This is — for the first time — a thin-layer, conducting, highly aligned film for high-performance, paintable, directly writeable plastic electronics,” said Jinsang Kim, a professor of materials science and engineering at the university. Kim led the research team whose findings were recently published in the journal, Nature Materials.
Semiconductors, though expensive to manufacture, form the backbone of electronic devices from computers to mobile phones and televisions to solar cells. As the Michigan researchers note, inorganic semiconductors require high temperatures during the manufacturing process and vacuum systems for processing into electronics. By contrast, plastic semiconductors can be prepared in common laboratory settings, but those plastic devices cannot deliver the performance of their inorganic counterparts. As Kim noted, charge carriers cannot move through plastics as easily as they can move through inorganic semiconductors, because in the plastic semiconductors, the semiconductor polymer molecules are randomly arranged. Charge carriers travel along polymer chains much more quickly than they can in random arrangements, Kim said.
To improve the carrier mobility, the researchers focused on aligning the semiconducting polymer molecules into a “charge-carrying freeway.” Kim and his team succeeded by designing a liquid polymer solution that would automatically align the semiconducting molecules with one another. With a single brush stroke, they say, the molecules assemble into high-performance semiconducting thin-layer films. By manipulating both the shape of the molecules and the way in which they are allowed to form films, the team succeeded in developing a paintable polymer semiconductor and applicator system.
Now that the team has successfully proven the concept, they must set about improving and optimizing it. Should it live up to its initial promise, the possibilities are endless.