Positive Reactions: New materials have the potential to transform electronics
For award-winning professor and researcher Dr. Suning Wang, nothing compares to the magic of chemistry.
“It’s really fun, especially in my lab. We apply light or heat to molecules and watch the reaction – they change colour, and become luminescent or fluorescent,” Wang says. “Further, we manipulate the structure and properties of molecules, which is even more amazing.”
Of particular note, the Wang Group lab in the Queen’s Department of Chemistry, which employs 11 students, has discovered new phenomena and materials with the potential to revolutionize electronics. This, in turn, supports the various processes involving big data by enabling enhanced technologies, especially for data display and information storage, Wang says.
One ground-breaking result of the lab’s research was the discovery of photochromic boron compounds. A student noticed during an experiment that a crystal was changing colour as it was exposed to light. “It went from the usual pale-yellow colour and got darker and darker until it was almost black. It surprised us and took us six months to figure out what had happened.”
The result? A fundamental discovery of what a molecule can do when exposed to light. “It underwent a structural and colour change, and remarkably, the change was reversible,” says Wang. “This type of compound has potential applications in erasable papers … and molecular switches, which can enable better information storage.”
Another unprecedented discovery, one the lab’s researchers are most proud of, came after an excited student called Wang to see something unexpected. They had been heating up a white solid, a boron and nitrogen compound that was not emissive. As the temperature went up, however, green fumes began to spew out, forming a fluorescent coating on top.
“When I saw it I was intrigued. I wondered, ‘Is this thing going to explode?’” Wang recalls with a laugh. “Bright green vapours coming out of a solid? I couldn’t believe it.” Analysis revealed that they’d discovered a new aromatic molecule formed via structural transformation of the original molecule under heat.
Wang’s lab can produce new and highly emissive materials using light as well. “This has potentially important applications in chemistry – for new ways to make materials, especially luminescent and semiconducting materials, which could then be used in organic devices.”
Building on this discovery, Wang’s team found a better way to make a new graphene-like material. Graphene was first isolated in 2004 and is often referred to as “a wonder material” because of its vast range of high-tech applications.
Wang and her team have created a simple, bottom-up method that could produce graphene-like materials byreplacing some carbon atoms with boron and nitrogen, using light or heat. The materials could potentially be used in electronics, semiconductors, mobile device displays, solar cells, fast-charging lithium-ion batteries, and sensing and imaging devices.
Currently, about half the Wang lab’s work focuses on designing and synthesizing novel compounds that emit blue luminescence for use in organic light emitting diodes (OLEDs), devices that convert electricity into light.
“Blue organic LED generates high-energy colour, and is the most difficult to achieve in the OLED industry,” Wang says. Advances would boost the commercialization of OLEDs, with far-reaching effects. “OLEDs are very efficient devices that consume little energy, and will be used more and more generally in cell phones and TVs, displays, and lights.”
Asked about futuristic applications for her new materials, Wang says flexible displays on devices is one example. “However, I think the fundamental impact is more on the energy side. You can use organic-based materials to make new solar cells that use renewable energy, or energy-efficient lighting devices.”
Fundamental discovery, or “a new trick by a molecule and a new phenomenon that no one has ever seen before,” is what she finds most rewarding about her work. “But it’s also great to think that in future, people can likely exploit these phenomena to discover new materials in chemistry – and eventually, apply them to the wider world.”
(e)Affect Issue 7 Spring 2015
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