报告题目: Improvement of Thermoelectric Properties of WSe₂ by Substitution in Cationic and Anionic Sublattices

报告人：Dr. Yakovleva Galina

       Institute of Inorganic Chemistry

       Siberian Branch of Russian Academy of Sciences

邀请人：王洪超

报告时间：2019-08-17 下午 2:30

报告地点：知新楼C座1111报告厅

报告内容: WSe₂ is viewed as potential thermoelectric (TE) material due to its excellent Seebeck coefficient (1067 μV/K) at room temperature. But the figure of merit (zT) for pure WSe₂ is only 0.0014 which is far for real application. Depending on sustained research, many effective ways are carried out to enhance the TE properties of WSe₂. Such as composite, elements substitution, forming intercalation and transition to two-dimensional materials. Among these strategies, Nb substitute of W is proved as an effective way to boost the zT of WSe₂ due to the sharply decreased carrier conductivity. Based on the Nb substitution, the dual doping of Nb and S for WSe₂ is reported in this presentation. W_1-xNb_xSe_2-yS_y (x = 0.02, 0.04, 0.06; y = 0.2, 0.3, 0.4, 0.5) samples are prepared via traditional melting method. The relationships between carrier concentration and electrical resistivity or Seebeck coefficient are discussed in detail in this presentation. The band structure which controlled by the carrier concentration is also presented. Additionally, the anionic substitution caused morphology change is responsible for the low lattice thermal conductivity which will be shown in this presentation. Finally, the zT of Nb and S co-doped WSe₂ reaches 0.25 at 600 K which is higher than other previous reports. Thus Nb and S substitution is proved as an effective way to enhance the TE properties of WSe₂.

报告人简介：Dr. Galina Yakovleva, graduates at Institute of Inorganic Chemistry at 2019 and gets her PhD degree. She received her Bachelor and Master degrees from Novosibirsk State Technical University at 2013 and 2015 respectively. Her current research interests include design and creation of a set up for measurements of temperature dependences of Seebeck coefficient at low temperature, temperature dependences of electrical conductivity or Seebeck coefficient of transition metal oxides and chalcogenides.