The magical material for the future – indium tin oxide (ITO). This ceramic material conducts electricity, but is transparent, this quality makes it crucial for the production of screens of all kinds. Mostly for smartphones and LCD televisions. This material is a byproduct of refining other metals—and the U.S. needs to import it from places like Canada and China. As a result, researchers have been looking for a viable ITO replacement for more than a decade, and it may be a super-thin layer of silver.
It’s not that indium is insanely expensive—it cost about $109 per pound on average last year, on the free market—nor is it incredibly rare.
Ioannis Kymissis, an associate professor of electrical engineering at Columbia University, says “its supply is fixed, because there’s no real primary source.”
A primary reason to search for an alternative is to “reduce the use of relatively scarce materials,” Kymissis says, with an eye towards sustainability. Another is that ITO isn’t good for flexible, bendable displays, because it’s brittle.
A professor of electrical engineering and computer science at the University of Michigan, just published new research in the journal Advanced Materials that suggests using a seven-nanometer-thick film made of silver could be the replacement. Silver is very electrically conductive, and is also surprisingly transparent in such a thin layer.
But if you try to spread silver out thinly on its own, it doesn’t behave nicely: it clumps into what Guo compares to islands. He solved that problem by mixing it with either copper or aluminum.
“And then this magic happens,” Guo says. “Now you look at the film, it’s very smooth.”
The professor says that his creation could also help make displays that are bendable: silver is quite ductile, and it can be deposited onto flexible plastic devices without the need to heat it up during the manufacturing process.
“Especially in the future, where more and more flexible devices are demanded,” he says, “I think that this could have a very good use.”