Targeted doping strategy use copper ions to boost thermoelectric performance

QUT researchers have identified a new method for incorporating copper ions into a germanium telluride thermoelectric material that significantly improves its ability to convert waste heat into electricity.

Germanium telluride is used in electronic devices to turn heat into electricity, helping save energy and power small devices.

In a study published in Nature Communications, the researchers detail the targeted “copper doping” strategy using copper ions.

Alongside first author Yongqi Chen, the QUT researchers contributing to the study include Professor Zhi-Gang Chen, Dr. Meng Li, Dr. Xiaodong Wang, and others.

Professor Zhi-Gang Chen said copper doping was the process in which small amounts of copper were added to a material to change its properties, such as improving its ability to conduct electricity.

Germanium telluride was known for its ability to convert heat into electricity but often did not work as well as it could because of the arrangement of the atoms, he said.

“Most materials lose energy because of the structure of how their atoms are arranged,” Professor Chen said.

Ms. Yongqi Chen said the targeted doping strategy in this study used copper ions to enhance thermoelectric performance of the material, offering a new pathway for efficient energy conversion of materials.

“Germanium telluride has natural flaws in its atomic structure that impact its performance in converting heat to electricity,” she said.

“By attaching copper ions into specific points in the material’s crystal structure, we were able to produce significantly more power than similar materials have before.”

Professor Chen said previous attempts at copper doping germanium telluride were “interstitial doping”—the insertion of copper ions between atoms in the lattice structure without replacing any of the existing atoms.

“In this study, we used an innovative solid solution strategy which precisely guided the copper ions to substitute existing atoms in the material,” Professor Chen said.

Professor Chen said in thermoelectrics, researchers calculate a material’s ability to convert heat into electricity, or vice versa, as the “figure of merit.”

“In this study, the new material achieved a high figure of merit of 2.3, compared to the previous version of this material which was 1.5,” Professor Chen said.

“So that’s an improvement of more than 50%.

“This technique sets out a path forward in which we can identify flaws in a material’s atomic structure. We can then use a solid solution treatment to precisely target an improvement to then produce a higher-performing material with few defects.”