Rattling-Induced Ultralow Thermal Conductivity Leading to Exceptional Thermoelectric Performance in AgIn5S8

Juneja, Rinkle and Singh, Abhishek K (2019) Rattling-Induced Ultralow Thermal Conductivity Leading to Exceptional Thermoelectric Performance in AgIn5S8. In: ACS APPLIED MATERIALS & INTERFACES, 11 (37). pp. 33894-33900.

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Abstract

Rattling has emerged as one of the most significant phenomenon for notably reducing the thermal conductivity in complex crystal systems. In this work, using first-principles density functional theory, we found that rattlers can be hosted in simpler crystal systems such as AgIn(5)S(8 )and CuIn5S8. Rattlers Ag and Cu exhibit weak and anisotropic bonding with the neighboring In and S and reside in a very shallow anharmonic potential well. The phonon spectra of these compounds have multiple avoided crossing of optical and acoustic modes, which are a signature of rattling motion. This leads to ultralow thermal conductivity, which is inversely proportional to mass and frequency span of rattling modes. Even though Ag atoms contribute to the valence band states, the rattler modes of Ag do not scatter carriers significantly, leaving the electronic transport virtually unaffected. Moreover, AgIn5S8 possesses a combination of heavy and light valence bands resulting in a very high power factor. A combination of favorable thermal and electronic transport results in a very high figure of merit of 2.2 in p-doped AgIn5S8 at 1000 K. The proposed idea of having rattlers in simpler systems can be extended to a wider class of materials, which would accelerate the development of thermoelectric modules for waste energy harvesting.

Item Type:	Journal Article
Publication:	ACS APPLIED MATERIALS & INTERFACES
Publisher:	AMER CHEMICAL SOC
Additional Information:	copyright for this article belongs to AMER CHEMICAL SOC
Keywords:	anisotropic bonding; rattling; thermal transport; electronic transport
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	22 Oct 2019 10:47
Last Modified:	22 Oct 2019 10:47
URI:	http://eprints.iisc.ac.in/id/eprint/63781

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