Research into the synthesis of new materials could lead to more sustainable and environmentally friendly products such as solar panels and light-emitting diodes (LEDs). Scientists at Ames National Laboratory and Iowa State University developed a colloidal synthesis method for alkaline earth alcogenides. Using this method, they can 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.
Alkaline earth alcogenides are a type of semiconductor that is of growing interest to scientists. They have a variety of potential 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, Ames Lab scientist and John D. Corbett Professor of Chemistry at Iowa State University, one of the reasons why these new materials are interesting is that “they are composed of earth-abundant and biocompatible elements, which makes them cheap Alternatives makes comparison to the more common toxic or expensive semiconductors.”
Vela explained that more common semiconductors contain lead or cadmium, both elements that are harmful to human health and the environment. Additionally, 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 from days to weeks,” he said.
On the other hand, Vela explained that “solution-phase (colloidal) chemistry can be performed at much lower (below 300 °C or 572 °F) temperatures and shorter reaction times.” So the colloidal method that Vela’s team used 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. Nanocrystal size is important because it determines the optical properties of some materials. Vela explained that by changing particle size, scientists can affect how well the materials absorb light. “This means we can potentially synthesize materials that are better suited for certain applications simply by changing the size of the nanocrystals,” 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 achieve this goal, they needed a deeper understanding of the basic chemistry of alkaline earth alkalcogenides. So they decided to focus on these binary materials instead.
Vela said her research fills a need to improve scientists’ understanding of photovoltaic, luminescent and thermoelectric materials, which are composed of earth-abundant and non-toxic elements. He said: “We hope that our developments in this project will ultimately contribute to the synthesis of more complex nanomaterials such as the alkaline earth chalcogenide perovskites.”
This research is further discussed in the article “Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability” written by Alison N. Roth, Yunhua Chen, Marquix AS Adamson, Eunbyeol Gi, Molly Wagner, Aaron J. Rossini and Javier Vela, and published in ACS nano.
Materials provided by DOE/Ames Laboratory. Note: Content can be edited for style and length.