Enhancement of thermoelectric figure-of-merit of graphene upon BN-doping and sample length reduction

Abstract

Using first-principles density functional perturbation theory based calculations of length-dependent lattice thermal conductivity (κL) and using our previously calculated results [R. D’Souza and S. Mukherjee, Phys. Rev. B 95, 085435 (2017)] of electrical transport, we report results of thermoelectric figure-of-merit (ZT) of monolayer and bilayer graphene. We find a nearly tenfold increase in ZT for the graphene sample doped with boron nitride and reduced sample length. We also compare κL calculated using the iterative real space method with conventional analytical Callaway-Klemens method and obtain the flexural (ZA) phonon modes to be dominant in thermal transport unlike in the latter method. Our calculations are in good agreement with available experimental data.