Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
Internal Online Seminar
Chair: Sebastian Mährlein

Friday, October 30, 2020, 11:00 am
Dr. Tanmoy Ghosh
Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, India
Low Thermal Conductive and High-performance Metal Chalcogenide Thermoelectrics
Thermoelectric energy generation and energy harvesting from waste heat is a promising technology for the management of electrical and thermal energies [1]. Waste heat is a ubiquitous natural by-product of our energy usage. Nearly two-third of the energy we produce gets irreversibly wasted as heat. Thermoelectric materials have the ability to convert this waste heat into useful electrical energy. While the underlying principles are known for a long time, achieving high thermoelectric conversion efficiency is a daunting task because of the requirement of co-existence of seemingly contradictory properties in a material: high electrical conductivity, high Seebeck coefficient and low thermal conductivity [2]. First, I will briefly discuss electronic structure modulation strategies to achieve high thermoelectric performance. One of the key requirements for a material to achieve high thermoelectric conversion efficiency is that it must have low lattice thermal conductivity. Early success came from the implementation of extrinsic phonon scattering methods by introducing micro-/meso-scale objects into the host matrix [3]. Intrinsic material properties, which induces anharmonic lattice vibration and reduces lattice thermal conductivity, are however much more beneficial for thermoelectric applications. In this talk, I will discuss these intrinsic mechanisms, like ferroelectric instability, rattling etc., and their effective implementation to achieve high thermoelectric performance in various metal chalcogenides like SnTe and GeSe [4,5]. I will also discuss the intrinsic origin of low thermal conductivity in all-inorganic halide perovskites based on their soft elastic layered structure and low phonon lifetime [6].
[1] J. He and T. M. Tritt, Science 357, eaak9997 (2017).
[2] G. J. Snyder and E. S. Toberer, Nature Materials 7, 105 (2008).
[3] K. Biswas, J. He, I. D. Blum et al., Nature 489, 414, (2012).
[4] A. Banik, T Ghosh, R. Arora et al., Energy Environ. Sci. 12, 589 (2019).
[5] D. Sarkar, T. Ghosh, S. Roychowdhury et al., J. Am. Chem. Soc. 142, 12237 (2020).
[6] P. Acharyya, T Ghosh, K. Pal et al., J. Am. Chem. Soc. 142, 15595 (2020).

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