Influence of the pore shape and dimension on the enhancement of thermoelectric performance of graphene nanoribbons
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ARTICLE Influence of the pore shape and dimension on the enhancement of thermoelectric performance of graphene nanoribbons Sukhdeep Kaur and Sukhleen Bindra Naranga) Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005, Punjab, India
Deep Kamal Kaur Randhawa Department of Electronics and Communication Engineering, Guru Nanak Dev University, RC Jalandhar, Ladhewali 144007, Punjab, India (Received 5 October 2016; accepted 28 December 2016)
There is a need to discover new thermoelectric materials that can convert waste heat into electrical energy. In this paper, study has been done to observe the effect of shape and dimension of nanopores embedded in graphene nanoribbons (GNRs) as to tune their thermoelectric performance that can lead to enhancement of thermoelectric figure of merit (ZT). It is observed that incorporation of pores in GNRs greatly reduces the thermal conductivity. Although the Seebeck coefficient decreases with the introduction of the pore while the conductance depends upon the pore shape, the decreasing trend in thermal conductivity leads to enhancement of thermoelectric performance. The aim of this work is to study the effect of various circular and the triangular shaped dimensions so as to tune the pore to its optimal dimension that would enhance the overall thermoelectric efficiency. Ballistic transport regime and semiempirical method using Huckel basis set is used to obtain the electrical properties while the Tersoff potential is used for the phononic system.
I. INTRODUCTION
Graphene is a two-dimensional one atom thick crystalline form of carbon which is the most abundant and widely studied material for use in the electronics industry.1 One promising route is to take advantage of reduced lattice thermal conductivity in low dimensional materials which can be obtained by nanostructuring it to create nanoribbons.1–5 This decrease could be further engineered in porous nanoribbons, since phonon thermal conductivity is reduced in nanoporous semiconductors.6 The parameter used to evaluate the thermoelectric performance of a material is dimensionless figure of merit ZT which is expressed as ZT 5 S2GT/k, where S is the Seebeck coefficient, G is electrical conductivity, T is temperature, and k is thermal conductivity. Here k is the summation of electron thermal conductivity (ke) and lattice or phonon thermal conductivity (kph). The quantity S2G is called the power factor (PF) which is the ability of a device to handle voltage and current. Thus a large ZT requires high S, high G, and low thermal conductivity. However these factors are correlated and thus it requires a delicate optimization to yield higher ZT values.7 Researchers have theoretically investigated many different methods of modulating the geometry of 1D Contributing Editor: Mauricio Terrones a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.3 J. Mater. Res., Vol. 32, No. 6, Mar 28, 2017
nanostructures including: rough surface,8,9 heterostructures,10 helical nanoconfiguration,
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