In a significant breakthrough for the electronics industry, researchers at Penn State have engineered a highly efficient thermoelectric cooler. This innovative device is poised to revolutionize cooling power and efficiency for future high-power electronics, which are expected to be smaller and more capable over time.
The key to this groundbreaking development lies in the use of half-Heusler alloys and a novel annealing process. These elements work together to enhance cooling power density and carrier mobility, making the cooler a promising solution for managing heat in next-generation electronics.
Bed Poudel, a research professor in the Department of Materials Science and Engineering at Penn State, spoke enthusiastically about the potential applications of this device. He said, “Our new material can provide thermoelectric devices with very high cooling power density. It is not just competitive in terms of technoeconomic measures but surpasses the current leading thermoelectric cooling modules. This development will greatly benefit the new generation of electronics.”
Thermoelectric coolers operate by transferring heat from one side of the device to the other when electricity is applied. This results in one side being distinctly cold and the other hot. When the cold side is placed on heat-generating electronic components, such as laser diodes or microprocessors, it effectively manages the temperature by pumping away excess heat.
The thermoelectric cooler developed by Penn State researchers has demonstrated an impressive 210% increase in cooling power density compared to its commercial counterpart made from bismuth telluride. It also maintains a similar coefficient of performance (COP), which is the ratio of useful cooling to the energy required. These findings were published in the journal Nature Communications.
Shashank Priya, vice president for research at the University of Minnesota and a co-author of the paper, highlighted the capabilities of the new device.
“This solves two out of the three big challenges in making thermoelectric cooling devices.”
“It provides high cooling power density with a high COP, meaning a small amount of electricity can pump a lot of heat. Also, for high-powered lasers or applications that require a lot of localized heat to be removed from a small area, this device offers the optimum solution.”
The new device is built using half-Heusler alloys, materials with unique properties ideal for energy applications like thermoelectric devices. These materials offer robust strength, thermal stability, and efficiency. The researchers used an innovative annealing process, which manipulates how materials are heated and cooled, to alter and control the material’s microstructure to eliminate defects.
This annealing process also significantly increased the material’s grain size, leading to fewer grain boundaries that reduce electrical or thermal conductivity. Wenjie Li, assistant research professor in the Department of Materials Science and Engineering at Penn State, explained this transformation: “Through this annealing process, we can control the grain growth from the nanoscale to the microscale — a difference of three orders of magnitude.”
Reducing grain boundaries and other defects greatly improved the carrier mobility of the material, which impacts how electrons can move through it, resulting in a higher power factor. This power factor is crucial in electronics-cooling applications as it determines the maximum cooling power density.
Li further elaborated on the significance of this breakthrough: “In laser diode cooling, a significant amount of heat is generated in a very small area, and it must be maintained at a specific temperature for optimal performance. That’s where our technology can be applied. This has a bright future for local high thermal management.”
The materials also produced the highest average figure of merit or efficiency, of any half-Heusler material in the temperature range of 300 to 873 degrees Kelvin (80 to 1,111 degrees Fahrenheit.) This demonstrates a promising strategy for optimizing half-Heusler materials for near-room-temperature thermoelectric applications.
“As a country, we are investing a lot in the CHIPS and Science Act, and one problem might be how microelectronics can handle high-power density as they get smaller and operate at higher power,” Poudel said. “This technology may be able to address some of these challenges.”
The project was supported by grants from various agencies including the Office of Defense Advanced Research Projects Agency, Office of Naval Research, U.S. Department of Energy, National Science Foundation, and the Army Small Business Research Program.
