First Principles Investigations of Structural, Electronic and Transport Properties of $$\hbox {BiI}_3/\hbox {ZrS}_2$$
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https://doi.org/10.1007/s11664-020-08479-y 2020 The Minerals, Metals & Materials Society
ASIAN CONSORTIUM ACCMS–INTERNATIONAL CONFERENCE ICMG 2020
First Principles Investigations of Structural, Electronic and Transport Properties of BiI3=ZrS2 van der Waals Heterostructure: A Thermoelectric Perspective GAUTAM SHARMA,1 SHOUVIK DATTA,1,2 and PRASENJIT GHOSH 1,2,3,4 1.—Department of Physics, Indian Institute for Research and Education, Pune, Maharashtra 411008, India. 2.—Centre for Energy Sciences, Indian Institute for Research and Education, Pune, Maharashtra 411008, India. 3.—e-mail: [email protected]. 4.—e-mail: [email protected]
Using density functional theory and semi-classical Boltzmann transport theory, we have studied structural, electronic and transport properties of a van der Waals vertical heterostructure of BiI3 and ZrS2 . The elastic constant of the heterostructure is larger than the individual monolayers. Further it has a direct band gap that is smaller than the monolayers. The interaction between the layers results in subtle changes in the electronic properties of the heterostructure such that its transport properties are also affected. In particular, we find that the relaxation time of electrons is significantly increased in the heterostructure such that its power factor is about ten and one hundred times larger than that of a monolayer of ZrS2 and BiI3 , respectively, indicating that the maximum power output from a thermoelectric device made of an ndoped heterostructure is larger than that obtained from the individual components. Our results suggest that this novel heterostructure is a possible candidate for n-type thermoelectrics. Key words: Thermoelectric, heterostructure, monolayer, power factor, ZrS2 , BiI3
INTRODUCTION With the decline in availability of fossil fuels and increase in environmental pollution caused by their use as a primary source of energy, there is a tremendous growth in research activities related to developing alternative technologies that can harness renewable sources of energy. Additionally, much energy is also wasted in the form of heat. Hence, there are significant research efforts to develop technologies that can use wasted heat energy and convert it into some other useful form. Amongst them, thermoelectric (TE) materials have attracted particular attention because of their thermoelectric effects, e.g. the Seebeck effect can be
(Received June 12, 2020; accepted September 9, 2020)
used to transform waste heat produced from industry, automobile engines, microprocessors, mobile phones, etc., directly into electrical energy.1,2 The efficiency of a TE material is determined by a dimensionless figure of merit, ZT ¼ a2 r T/j, where a denotes the Seebeck coefficient, r the electrical conductivity, T the absolute temperature and j the total thermal conductivity, which is the sum of the contributions from the carrier (je ) and lattice (jL ) thermal conductivities.3 The higher the value of ZT for a TE material, the better will be its performance. Amongst the above m
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