Shenzhen Business Daily • Reading Client Chief Reporter Wu Ji Correspondent Xu Xinwen
On April 5, the top international journal Science published two research papers from the Department of Physics of Southern University of Science and Technology at the same time. The team of Chair Professor He Jiaqing of the Department of Physics published an article explaining how they have obtained high-performance thermoelectric materials through new physical mechanisms. The research group of Associate Professor Lin Junhao from the Department of Physics of SUSTech and the Guangdong-Hong Kong-Macao Greater Bay Area Quantum Science Center and his collaborative team published an article documenting their major breakthroughs in the design, synthesis and structural elucidation of two-dimensional all-organic perovskites.
In this work, Jiaqing He's team discovered and verified for the first time the mechanism of hole carrier capture and release, its regulatory effect on the electrical properties of materials, and the inhibitory effect of pseudonanostructures regulating the lead vacancy morphology of materials on thermal transport of materials. The team used the lattice distortion of the material to realize the dynamic regulation of hole carriers to optimize the electrical properties, and induced the intrinsic point defects of the materials to fabricate widely distributed pseudo-nanostructures to optimize the thermal properties, both of which provide feasible ideas for the performance optimization of other thermoelectric materials. At the same time, the improvement of the structural design and conversion efficiency of thermoelectric devices will also help to promote the development and application of thermoelectric power generation devices.
According to He Jiaqing, they constructed a large number of nanoscale vacancy clusters in the lead telluride material, which generated a large number of stresses and strains in the material, which significantly reduced the lattice thermal conductivity of the material and was more conducive to the high service of the thermoelectric material. During the experiment, the team also stumbled upon an eccentric structure when germanium doped into the lead telluride lattice, which can trap the carriers at low temperatures, reduce the concentration of free carriers, and release the carriers at high temperatures. In this method, the capture and release of carriers are realized by lattice distortion, which makes it an intrinsic property of the material.
Lin Junhao's team and collaborators jointly overcome the bottleneck of the difficulty of stabilizing the two-dimensional all-organic perovskite structure. There are two major breakthroughs in this study. First, the researchers synthesized two-dimensional all-organic perovskite crystals for the first time, expanding the field of perovskite materials and laying a foundation for the future development of new all-organic two-dimensional perovskite materials. Secondly, based on the fine characterization of these materials, the team has opened up a new field of cryo-EM technology for the characterization of organic groups in chemical organic materials.
"To the best of our knowledge, this is the best record of high-resolution low-dose imaging to date. Previously, even the most sensitive organometallic frameworks had a dose tolerance of more than 10 electrons/square angs, while organic and inorganic hybrid crystals had a dose tolerance of nearly 50 electrons/square angstroms under freezing conditions. "The research team has extended high-resolution, low-dose imaging techniques to the field of all-organic crystals, providing a good example for the structural characterization of this more sensitive organic material.
Jiaqing He's research group
At present, Jiaqing He is mainly engaged in the research of transmission electron microscopy, thermoelectric materials and the correlation between structure and physical properties, and has made a series of major breakthroughs. Since joining SUSTech, he has published 5 "Science" articles as a corresponding author, and co-authored 3 "Science" and 3 "Nature" as the main author. In the future, Jiaqing He's team will conduct more profound and comprehensive mechanism research, with the help of high-quality single crystal materials and advanced characterization methods, to conduct in-depth exploration of electrons and phonons of thermoelectric materials, so as to provide a more effective method for the realization of electroacoustic decoupling control.
Junhao Lin's research group
Lin Junhao's main research interests include the development of new methods and technologies for transmission electron microscopy, in-situ characterization of atoms under extreme conditions, and accurate measurement of quantum physical properties of low-dimensional quantum materials. Lin Junhao said that his team plans to carry out the source research and development of advanced characterization instruments, such as the development of a high-stability transmission electron microscope device near the temperature of liquid helium, which can be used to observe low-temperature physical phenomena and solve important scientific problems in quantum materials.
It is worth mentioning that the two professors not only blossom simultaneously in scientific research achievements, but also tacit partners in daily administrative work. He Jiaqing has served as Secretary of the Party Committee of the Faculty of Science since 2018 and Head of the Department of Physics since 2015, while Lin Junhao has served as Secretary of the Party Branch of the Department of Physics since 2018 and will continue to serve as Secretary of the Party Committee of the Department of Physics and Deputy Director of Administration of the Department of Physics after the establishment of the Party Committee of the Department of Physics in 2021. They have supported each other, worked together to cope with difficulties, and constantly improved the rules and regulations of the department, making great contributions to the steady development of the Department of Physics. At the same time, the two professors are also typical examples of SUSTech's "double leaders" and "double shoulders" training.
Driven by many outstanding professors such as He Jiaqing and Lin Junhao, more and more high-quality achievements have emerged in the Department of Physics of SUSTech. Up to now, the Department of Physics has published 30 papers in the journals Nature and Science, of which 15 have been published by the Department of Physics as the first or corresponding unit. Especially in just four months this year, the Department of Physics has published 1 "Nature" and 2 "Science".