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This film, University of Buffalo, Photovoltaics, LEDs, nontoxic material, develop films, strong light absorption, charge transport

New Thin Films Show Promising Properties For Photovoltaics, LEDs

Researchers at the University at Buffalo used a nontoxic material to develop films showing strong light absorption and charge transport.

Researchers are constantly searching for new materials that can make electronic devices more efficient and cheaper to build, especially as silicon nears the limits of its performance. To this end, scientists at the University at Buffalo have created new thin films from a little-used but abundant material, the performance of which show promise for use in electronic and optical applications such as photovoltaics and light-emitting diodes (LEDs).

A barium zirconium sulfide thin film created by a research team at the University at Buffalo that shows novel electronic properties. (Image source: Douglas Levere / University at Buffalo)

The team, led by Hao Zeng--professor of physics in the university’s College of Arts and Sciences--created the films using barium zirconium sulfide, a category of materials known as chalcogenide perovskites. These materials have benefits over others used in electronic and photovoltaic devices, including that they are nontoxic and found naturally and abundantly in the earth. 

Indeed, researchers have been exploring the use of perovskite-based thin films in solar cells for years because of their potential for higher efficiency and less cost in cell production.

The films developed by Zeng’s team combine significant light absorption with good charge transport, which makes them well-suited for applications in which silicon is used today. “For many decades, there have been only a handful of semiconductor materials that have been used, with silicon being the dominant material,” Zeng said. “Our thin films open the door to a new direction in semiconductor research. There’s a chance to explore the potential of a whole new class of materials.”

Old Material, New Use

The researchers were not the first to discover barium zirconium sulfide and its usefulness; the compound has been used in applications dating back to the 1950s, but has been largely overlooked by scientists. “It has existed for more than half a century,” Zeng said. “Among earlier research, a company in Niagara Falls produced it in powder form. I think people paid little attention to it.”

However, powder is not the best form for the applications for which Zeng and his team wanted to use the material, so they set out to explore the material’s potential for thin films. The researchers crafted their films by using a laser to heat up and vaporize barium zirconium oxide, then depositing that vapor on a sapphire surface. This formed a film that was then converted into the final material through a chemical reaction called sulfurization.

The team published a paper on its work in the journal Nano Energy.

Researchers think their films will be especially useful for solar-energy generation, as research suggests this type of perovskite material would be much more efficient at converting sunlight into electricity than traditional silicon-based materials with identical thicknesses, said Haolei Hui, a physics PhD student and one of the team’s researchers. “Semiconductor research has traditionally been highly focused on conventional materials,” he said. “This is an opportunity to explore something new. Chalcogenide perovskites share some similarities to the widely researched halide perovskites, but do not suffer from the toxicity and instability of the latter materials.”

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

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