(558c) Thermoelectric Nanocomposites of Layered Chalogenide Bi2(Te/Se)3 Nanoplateletes and Their Interfacial Effects

Thermoelectric nanocomposites of layered chalogenide Bi₂(Te/Se)₃nanoplateletes and their interfacial effects

Ajay Soni^1,2 and Qihua Xiong *^,2,3

¹ School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh 175001, India

² Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore

³Division of Microelectronics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

* To whom the correspondence should be addressed. Email address: Qihua@ntu.edu.sg,

Recently the interests in layered chalcogenide materials have grown very rapidly. The compounds of chalcogenides (S, Te and Se) with Bi and Sb are of interests for topological insulators, thermoelectric (TE) applications, while the compounds with transition metals are of interests for optoelectronic applications. The observed fascinating physical properties are arising mainly due to the anisotropic crystal structures, weak van der Waals stacking of layer and quantum confinement effects in atomic thin layers. Historically, chalcogenide materials have been known as good TE materials, especially the family of (Bi/Sb)₂(Te/Se)₃ alloys which showed a competitive performances for room temperature TE applications.¹ The efficiency of the TE material is quantified by a dimensionless TE figure of merit, ZT = S²s/k, where S is the Seebeck coefficient, s is the electrical conductivity and k is the thermal conductivity. All three of the physical parameters are strongly dependent on the number of charge carriers (doping) and the arrangements of interfaces/grain boundaries. Thus the interplay of the three physical parameters leads to a very complex situation for engineering of charge and heat carriers in TE materials. For the new class of thermoelectric (TE) nanocomposites,^1-3 while the energy filtering by interfaces and grain boundaries is playing a vital role for enhancing the performances of TE materials, the thermodynamical instability of grain boundaries limits the application range and performance reproducibility.¹ To highlight this theme, we will present our work on the enhanced thermoelectric properties of chemically synthesized 2D n-type Bi₂(Te/Se)₃ nanoplatelet composites² and the effects of the thermodynamic environment during spark plasma sintering on the TE performance of Bi₂Te_2.7Se_0.3 nanoplatelet composites.³ Our studies emphasize on a unique coupling charge carriers and phonons and a subtle understanding of the interface crystallization, grain growth and energy filtering from the thermoelectric interfaces.

1.   Dresselhaus, M. S., Adv. Mater. 2007, 19, 1043-1053.

2.   Soni, A.; Yanyuan, Z.; Ligen, Y.; Aik, M. K. K.; Dresselhaus, M. S.; Xiong, Q., Nano Letters 2012, 12 (3), 1203-1209.

3.   Soni, A.; Yiqiang, S.; Ming, Y.; Yanyuan, Z.; Ligen, Y.; Xiao, H.; Zhili, D.; Aik, M. K. K.; Dresselhaus, M. S.; Xiong, Q., 2012, 12 (8) 4305.