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Development of a Novel Material with Thermoelectric Conversion Capacity by Controlling its Two-Dimensional Structure

  • 조회. 113
  • 등록일. 2020.12.23
  • 작성자. External Relations Team

- A research team led by Dr. Jeongmin Kim introduces a technique for controlling the laminating structure of niobium diselenide (NbSe2), a two-dimensional transition metal chalcogen compound
- expecting to contribute to energy harvesting and thermoelement commercialization

 

Picture 1. Dr. Jeongmin the Division of Nanotechnology, DGIST

 

 

 Research teams led by Dr. Jeongmin Kim of the Division of Nanotechnology and Prof. Woo young Lee of the Department of New Materials, Yonsei University, developed a novel material with thermoelectric conversion capacity by controlling the laminating two-dimensional structure of the transition metal chalcogen compound, which is a next-generation semiconductor material. The research is expected to contribute to the development of energy harvesting technique and thermoelement commercialization, with precise temperature control and a simultaneous heating-cooling system. 

 Recently, nanomaterials with electrical properties and strength similar to graphene are being extensively studied. Among these nanomaterials, the chalcogen compound, which is a two-dimensional transition metal, is known to have multiple band structures and various electrical properties depending on the interatomic bonding direction and laminating structure; thus, it is now emerging as a next-generation energy material. The applications of the material are countless, particularly due to the existing bandgap in the semiconductor. A bandgap, a specific energy region that controls the flow of electrons inside the material, is an essential property for the practical applications of an electronic device. 

 And among the nanomaterials based on the chalcogen compound, the 2H-phase niobium diselenide (2H-NbSe2) is gaining attention. However, due to the metallic band structure with a low Seeback coefficient, its thermoelectric conversion capacity is low and hence, its commercialization is limited. 

 Therefore, the research teams jointly manufactured a novel polymorph of niobium diselenide by transforming the metallic band structure into a semimetallic band structure that is suitable for thermoelectric conversion. The research teams successfully synthesized the 2H-3R form of the transformed compound by mixing the existing 2H laminating structure with the 3R laminating structure of a new form via a solid reaction method conducted at high temperature. Through this approach, the thermoelectric Seeback coefficient improved by approximately 40 µV/K, as compared with the existing 2H laminating structure; additionally, the rate of change of the thermoelectric capacity in terms of the exterior field-effect significantly increased. 

 Dr. Kim stated, “We are the first to discover the fact that the electron band structure and electric transport property can be controlled by transforming the electron band structure of a polymorph based on the laminating structure control of the identical material,” and also revealed that “The research will contribute to the application of energy harvesting technique of the two-dimensional material”

 Furthermore, Hongjae Moon, a Ph.D. candidate in the Department of New Materials at Yonsei University, participated in the research, while the research was published in ‘Nano Energy’ on December 1.
 

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