New US study to focus on new QD materials
University of Arkansas team hope to replace toxic elements with more benign ones such as copper, indium and zinc
University of Arkansas chemistry professors Colin Heyes and Robert Coridan will use a $535,560 award from the US National Science Foundation to characterise the structural, optical and electronic properties of semiconducting nanoparticles composed of three or more elements.
They hope the research will lead to new materials for use in light-emitting diodes, lasers, solar-energy conversion, catalysis, chemical and biochemical sensors and biomedical imaging.
“Our goal is to replace toxic elements commonly used in semiconducting nanoparticles, such as cadmium, with more benign ones, such as copper, indium and zinc,” said Heyes, a spectroscopist who measures single nanoparticle optical properties using extremely sensitive fluorescence microscopy.
“However, much less is known about how to control the optical and electronic properties of nanoparticles incorporating these elements.”
Heyes, Coridan and their students will address this lack of knowledge by systematically varying the chemical synthesis of the nanoparticles and analysing how this affects the resulting atomic structure and, in turn, the optical and electronic properties.
Combining advanced chemical synthesis and analysis tools, they will study quantum dots made of copper-(zinc)-indium chalcogenide and silver-(zinc)-indium chalcogenides. Chalcogenides are compounds formed from chalcogen element atoms, which include sulphur, selenium and tellurium.
Two critical gaps in the understanding of these types of quantum dots are the mechanism underlying the ion-exchange/alloying and the relationship between the structure resulting from the specific reaction conditions and the electronic structure/exciton decay pathways. The researchers’ study will examine these knowledge gaps by systematically synthesising homogeneously alloyed and heterogeneous/gradient alloyed quantum dots.
“X-ray techniques are well suited to improve our understanding of how the elements are distributed in the nanoparticle, since we can use them to determine the exact oxidation state and immediate environment of these elements at the atomic level,” said Coridan, an expert in X-ray structural analysis.
“This can then be correlated to the optical and electrical properties of a single nanoparticle,” Heyes said.