Unit cells and electron micrographs of alkaline-earth chalcogenide nanocrystals. Image: US Department of Energy Ames National Laboratory.
Unit cells and electron micrographs of alkaline-earth chalcogenide nanocrystals. Image: US Department of Energy Ames National Laboratory.

Research into the synthesis of new materials could lead to more sustainable and environmentally friendly items such as solar panels and light emitting diodes (LEDs).

Scientists from Ames National Laboratory and Iowa State University have developed a colloidal synthesis method for alkaline earth chalcogenides. This method, reported in a paper in ACS Nano, 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 their purity and optical properties.

Alkaline earth chalcogenides are a type of semiconductor that is of growing interest among scientists. They have a variety of possible applications, including in bioimaging, LEDs and thermal sensors, and may also be used to make optical materials such as perovskites, which convert light into energy.

According to Javier Vela, Ames Lab scientist and a professor of chemistry at Iowa State University, one reason these new materials are of interest is because “they are comprised of Earth-abundant and biocompatible elements, which make them favorable alternatives compared to the more widely used toxic or expensive semiconductors”.

Other semiconductors contain lead or cadmium, which are detrimental to human health and the environment. What is more, the most popular technique scientists use to synthesize these materials involves 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,” Vela said.

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

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

The team’s original 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. So, they chose to focus on these binary materials instead.

Vela said that their research could help to improve scientists’ understanding of photovoltaic, luminescent and thermoelectric materials that are made of Earth-abundant and non-toxic elements. “We hope that our developments with this project ultimately aid in the synthesis of more complex nanomaterials, such as the alkaline-earth chalcogenide perovskites,” he said.

This story is adapted from material from Ames National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.