On May 26, 2023, Science reported the latest progress made by Prof. Zhao Lidong’s group from the School of Material Science and Engineering of Beihang University, in the field of electronic cooling materials and devices. The work titled “Lattice plainification advances highly effective SnSe crystalline thermoelectrics” introduces the concept of “lattice plainification”. It demonstrates that Cu can fill Sn vacancies to weaken defects scattering and boost carrier mobility, facilitating a power factor exceeding ~100 microwatts per centimeter per square kelvin and a dimensionless figure of merit (ZT) of ~1.5 at 300 kelvin, with an average ZT of ~2.2 at 300 to 773 kelvin. Liu Dongrui, a 2021 graduate student of Beihang University, is the first author, and Qin Bingchao, a 2019 doctoral student of Beihang University and Prof. Zhao Lidong, are the corresponding authors. The School of Materials Science and Engineering, Beihang University, is the first affiliation. This is the eighth paper published in Science by Prof. Zhao's research group since 2015.

Thermoelectric cooling uses the Peltier effect to directly convert electrical energy into heat energy. The fact that TEC systems are current-controlled leads to a series of benefits. Because the flow of heat is directly proportional to the applied DC current, heat may be added or removed with accurate control of the direction and amount of electrical current. Due to its advantages of precise temperature control, flexible size, diverse structures, and localized cooling, thermoelectric cooling technology has a stronger competitive advantage than traditional mechanical compression-based cooling technology in key areas such as precision guidance, sensors, and 5G optical modules. Therefore, the development of high-performance cooling materials and improvement of cooling efficiency of cooling devices are of great significance in key areas related to technological self-reliance.

Fig. 1 Peltier electronic cooling model

The group discovered tin selenide (SnSe) crystals with potential power generation and Peltier cooling performance. The extensive off-stoichiometric defects have a larger impact on the transport properties of SnSe, which motivated them to develop a lattice plainification strategy for defects engineering. They demonstrated that Cu can fill Sn vacancies to weaken defects scattering and boost carrier mobility, facilitating a power factor exceeding ~100 microwatts per centimeter per square kelvin and a dimensionless figure of merit (ZT) of ~1.5 at 300 kelvin, with an average ZT of ~2.2 at 300 to 773 kelvin. They further realized a single-leg efficiency of ~12.2% under a temperature difference (ΔT) of ~300 kelvin and a seven-pair Peltier cooling ΔTmax of ~61.2 kelvin at ambient temperature. Their observations are important for practical applications of SnSe crystals in power generation as well as electronic cooling.

Fig. 2 Significant increase in carrier mobility achieved by lattice plainification strategy

In the same issue ofScience, Professor In Chung from Seoul National University, Korea, published an opinion paper titled "Plainly Fixing Crystal Lattices" as a highlight report on this work. The paper highly praised this research work using adjectives such as "game-changer," "ground-breaking," "breakthrough," and "milestone." It pointed out that the "lattice plainification" strategy provides a paradigm shift in the development of new thermoelectric cooling materials and the optimization of devices and has milestone significance.

Fig. 3 (A) Comparison of power generation efficiency; (B) Comparison of cooling temperature difference between devices based on SnSe and Bi2Te3 materials

This research was jointly conducted by Professor Gao Xiang's research group from the Center for High Pressure Science & Technology Advanced Research, Professor Ge Zhenhua's research group from Kunming University of Science and Technology, and Researcher Wang Dongyang from Zhengzhou University. The research was mainly supported by the Central Program in Basic Science of National Natural Science Foundation of China, the National Natural Science Foundation of China, etc.

Link to the article: https://www.science.org/doi/10.1126/science.adg7196

Reviewed by Li Jianwei

Edited by Jia Aiping

Translated by Wen Li