Improved understanding of new visual materials

The investigation into the production of new materials could pave the way for more sustainable and environmentally friendly products such as light-emitting diodes (LEDs) and solar panels.

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

researchers from Ames National Laboratory Iowa State University formulated a colloidal synthesis technique for alkaline earth chalcogenides. This technique enables them to regulate the size of the nanocrystals in the material. They were also able to examine the surface composition of the nanocrystals and evaluate the purity and optical properties of the materials in question.

Researchers are increasingly interested in alkaline earth chalcogenides, a type of semiconductor with various potential applications such as LEDs, bio-imaging and thermal sensors. Alkaline earth chalcogenides can also be used to produce optical materials such as perovskite, which convert light into energy.

According to Javier Vela, John D. Corbett Professor of Chemistry at Iowa State University and Ames Laboratory Scientist, one reason these new materials are gaining interest is: “They are composed of abundant earth and biocompatible elements, making them favorable alternatives compared to the widely used toxic or expensive semiconductors.”

Villa explained that the most commonly used semiconductors include cadmium or lead, both of which are an element harmful to human health and the environment. Furthermore, the most common method that researchers use to create these materials requires solid-state reactions.

These reactions often occur at extremely high temperatures (above 900°C or 1652°F) and require reaction times that can last anywhere from days to weeks.

Javier Villa, Scientist, Ames National Laboratory

On the other hand, Villa explained it “Solution (colloid) phase chemistry can be done using much lower temperatures (below 300°C or 572°F) and shorter reaction times.” The colloidal technology used by Vela’s team requires less time and energy to produce the material.

Villa’s team learned that the colloid synthesis technique enabled them to regulate the size of the nanocrystals. This is vital as it determines the optical features of a particular material. Villa showed that by varying the particle size, researchers can influence how well materials capture light.

This means that we can manufacture materials more suitable for specific applications just by changing the size of the nanocrystal.

Javier Villa, Scientist, Ames National Laboratory

Villa says the team’s primary goal is to create an alkaline-earth semiconducting chalcogenide perovskite due to its potential application in solar equipment. However, they required a deeper look into the basic chemistry of alkaline-earth chalcogenides to achieve this goal. So they decided to focus on these binary materials instead.

Villa stated that their study meets a demand to increase scientists’ understanding of luminescent materials, photovoltaics, and thermoelectric materials that are composed of earth-rich, non-toxic elements.

We hope that our developments with this project will eventually assist in the synthesis of more complex nanomaterials, such as alkaline earth chalcogenide perovskite.

Javier Villa, Scientist, Ames National Laboratory

magazine reference

Roth, A.N., and others. (2022) Alkaline earth chalcogenide-containing nanocrystals: solution phase synthesis, surface chemistry, and stability. ACS Nano. doi.org/10.1021/acsnano.2c02116.

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