Low-Temperature Method to Make High-Performance Thermoelectric Materials

To date, thermoelectric materials have been produced using energy-intensive and costly methods. Baran, Nugraha, and their coworkers have created an innovative thermoelectric material formed by spin-coating a liquid solution of nanomaterials known as quantum dots.

The researchers spin-coated a thin lead-sulfide quantum dot layer on a surface and subsequently added a short linker ligand solution that crosslinks the quantum dots together to improve the electronic properties of the material.

Once the spin-coating process is repeated layer by layer to produce a 200-nm-thick film, the film is dried and fabrication is completed by gentle thermal annealing.

Thermoelectric research has focused on materials processed at very high temperatures, above 400 degrees Celsius.

Mohamad Nugraha, Postdoctoral Researcher, KAUST

The thermoelectric material, which is based on quantum dots, is heated by up to 175 °C. Such a lower processing temperature could reduce production costs and implies that it could be possible to form thermoelectric devices on a wide array of surfaces such as inexpensive flexible plastics.

The material developed by the team exhibited promising thermoelectric properties. A good thermoelectric material’s crucial parameter is the Seebeck coefficient, which is the amount of voltage produced upon applying a temperature gradient. “We found some key factors leading to the enhanced Seebeck coefficient in our materials,” stated Nugraha.

The researchers could also demonstrate that an effect known as the quantum confinement, which changes the electronic properties of a material upon being shrunk to the nanoscale, had a vital role in improving the Seebeck coefficient. According to Nugraha, the finding is a step toward practical low-temperature, high-performance, solution-processed thermoelectric generators.

A low-temperature method for enabling high-performance thermoelectric materials to recapture lost energy. (Video credit: © KAUST 2019)