Cross-plane enhanced thermoelectricity and phonon suppression in graphene/MoS 2 van der Waals heterostructures
Year: 2016
Type: article
Abstract: The thermoelectric figures of merit of pristine two-dimensional materials are predicted to be significantly less than unity, making them uncompetitive as thermoelectric materials. Here we elucidate a new strategy that overcomes this limitation by creating multi-layer nanoribbons of two different materials and allowing thermal and electrical currents to flow perpendicular to their planes. To demonstrate this enhancement of thermoelectric efficiency ZT , we analyse the thermoelectric performance of monolayer molybdenum disulphide (MoS 2 ) sandwiched between two graphene monolayers and demonstrate that the cross-plane (CP) ZT is significantly enhanced compared with the pristine parent materials. For the parent monolayer of MoS 2 , we find that ZT can be as high as approximately 0.3, whereas monolayer graphene has a negligibly small ZT . In contrast for the graphene/MoS 2 /graphene heterostructure, we find that the CP ZT can be as large as 2.8. One contribution to this enhancement is a reduction of the thermal conductance of the van der Waals heterostructure compared with the parent materials, caused by a combination of boundary scattering at the MoS 2 /graphene interface which suppresses the phonons transmission and the lower Debye frequency of monolayer MoS 2 , which filters phonons from the monolayer graphene. A second contribution is an increase in the electrical conductance and Seebeck coefficient associated with molybdenum atoms at the edges of the nanoribbons.
Source: 2D Materials
Authors: Hatef Sadeghi, Sara Sangtarash, Colin J Lambert
Institution: Lancaster University
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
Awards: Putting spin into carbon nanoelectronics, G1530137628, G1893551499, Supramolecular Nanorings for Exploring Quantum Interference, G6479653053, G6536352298, Molecular quantum devices, Quantum Effects in Electronic Nanodevices (QuEEN), "MOLECULAR-SCALE ELECTRONICS: Concepts, Contacts and Stability ""MOLESCO"""
OpenAlex ID: W2548639702