Penn State research shows strontium may be key to broad use Metal Tech News Weekly Edition – July 1, 2020
Since the outbreak of COVID-19, ultraviolet light has emerged as a popular way to kill novel coronavirus without the use of harsh chemicals. While research has shown that UV light is an effective destroyer of viruses and bacteria, the devices that emit a strong enough dose to get the job done tend to be bulky and expensive.
"You have to ensure a sufficient UV light dose to kill all the viruses," said Roman Engel-Herbert, Penn State associate professor of materials science, physics and chemistry. "This means you need a high-performance UV LED emitting a high intensity of UV light, which is currently limited by the transparent electrode material being used."
Herbert and his Penn State colleagues have discovered that strontium, a metallic element most people have never heard of, may be the solution to creating a better transparent electrode and thus a more effective virus killing UV device.
Currently, the devices that emit enough UV radiation to neutralize viruses and bacteria use an expensive mercury-containing gas discharge lamp, which requires high power, has a relatively short lifespan, and is bulky.
With the COVID-19 pandemic prompting individuals and institutions to look for an effective non-chemical way to sanitize everything from smartphones to hospital rooms, Penn State researchers to a look into developing high performance UV light emitting diodes that are more portable, long-lasting, energy efficient, and environmentally benign.
LEDs transparent to visible light are currently being used in computer monitors, smartphones, and other devices. While developing LEDs transparent to visible light was challenging, this level of difficulty increases substantially when you get to the ultraviolet band of light.
"There is currently no good solution for a UV-transparent electrode," said Joseph Roth, Ph.D. candidate in Materials Science and Engineering at Penn State. "Right now, the current material solution commonly employed for visible light application is used despite it being too absorbing in the UV range. There is simply no good material choice for a UV-transparent conductor material that has been identified."
A recent breakthrough in the search for new material, however, may change that.
Working with a materials theorist from the University of Minnesota, Penn State scientists recognized that the solution might lie in a recently discovered new class of transparent conductors already being studied as way to disinfect water.
When theoretical predictions pointed to the material strontium niobate, a highly water insoluble crystalline form of strontium, the researchers reached out to collaborators in Japan to receive strontium niobate films.
While early tests of these films show promise as UV transparent conductors, coming up with a method to create these films on a large scale would be necessary for commercial application.
A common industrial technique for creating thin films known as sputtering is showing promise to create the films and thus the transparent electrode needed to created low costs UV LEDs on the scale to fight COVID-19 and other disease.
"While our first motivation in developing UV transparent conductors was to build an economic solution for water disinfection, we now realize that this breakthrough discovery potentially offers a solution to deactivate COVID-19 in aerosols that might be distributed in HVAC systems of building," Roth explains. Other areas of application for virus disinfection are densely and frequently populated areas, such as theatres, sports arenas, and public transportation vehicles, such as buses, subways and airplanes."