Basic research improves understanding of new optical materials

Basic research improves understanding of new optical materials

Unit cells and electron micrographs of alkaline earth chalcogenide (AeCh) nanocrystals. Credit: US Department of Energy Ames National Laboratory

Research into the synthesis of new materials could lead to more durable and greener products, such as solar panels and light-emitting diodes (LEDs). Scientists at Ames National Laboratory and Iowa State University have developed a method for the colloidal synthesis of alkaline earth chalcogenides. This method allows them to control the size of the nanocrystals in the material. They were also able to study the surface chemistry of the nanocrystals and assess the purity and optical properties of the materials involved. Their research is discussed in “Alkaline-Earth Chalcogen Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability,” published in ACS Nano.

Alkaline earth chalcogens are a type of semiconductor that is of increasing interest among scientists. They have a variety of possible applications, such as bioimaging, LEDs, and thermal sensors. These compounds can also be used to make optical materials, such as perovskites, that convert light into energy.

According to Javier Vela, an Ames Lab scientist and the John D. Corbett Professor of Chemistry at Iowa State University, one of the reasons these new materials are of interest is that “they are composed of biocompatible and earth-abundant elements, which what makes them favorable alternatives in comparison. to the more toxic or expensive semiconductors used”.

Vela explained that widely used semiconductors contain lead or cadmium, both of which are harmful to human health and the environment. Furthermore, the most popular technique scientists use to synthesize these materials involves solid-state reactions. “These reactions often occur at extremely high temperatures (over 900 °C or 1652 °F) and require reaction times that can last anywhere from days to weeks,” he said.

On the other hand, Vela explained that “solution-phase (colloidal) chemistry can be achieved using much lower temperatures (below 300 °C or 572 °F) and shorter reaction times.” So the colloidal method used by Vela’s team requires less energy and time to synthesize the materials.

Vela’s team found that the colloidal synthesis method allowed them to control the size of the nanocrystals. The size of the nanocrystal is important because it determines the optical properties of some materials. Vela explained that by changing the size of the particles, scientists can influence how well materials absorb light. “This means we can synthesize materials that are better suited for specific applications just by changing the size of the nanocrystal,” he said.

According to Vela, the team’s initial goal was to synthesize semiconducting alkaline-earth chalcogenide perovskites because of their potential use in solar devices. However, to accomplish this goal, they needed a deeper understanding of the fundamental chemistry of alkaline earth chalcogenides. Instead, they chose to focus on these binary materials.

Vela said their research fulfills a need to improve scientists’ understanding of photovoltaic, luminescent and thermoelectric materials that are made from earth-abundant and non-toxic elements. He said: “We hope that our developments with this project will eventually help in the synthesis of more complex nanomaterials such as alkaline earth chalcogenide perovskites.”

Authors of the study included Alison N. Roth, Yunhua Chen, Marquix AS Adamson, Eunbyeol Gi, Molly Wagner, Aaron J. Rossini and Javier Vela.

Chemists use abundant, cheap and non-toxic elements to synthesize semiconductors

More information:
Alison N. Roth et al., Alkaline-Earth Chalcogen Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability, ACS Nano (2022). DOI: 10.1021/acsnano.2c02116

Provided by Ames Laboratory

Citation: Fundamental research improves understanding of new optical materials (2022, September 20) Retrieved September 21, 2022, from

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