Buckled hexagonal carbon selenium nanosheet for thermoelectric performance

Abstract

Buckled hexagonal CSe nanosheet made of earth-abundant elements is investigated for thermoelectric performance by employing the first-principle calculations and the Boltzmann transport theory. The buckled hexagonal CSe sheet is shown to be an indirect-gap semiconductor with a lattice constant of 3.07 A and band gap of 1.51 eV. The maximum power factor of n-type (p-type) CSe sheet is 618 to 483 (9.87 to 7.42) mW m $$^{-1}$$ K $$^{-2}$$ at the temperatures from 300 to 700 K at the carrier concentration of about $$1.17\times 10^{13}$$ ( $$1.24\times 10^{13}$$ ) cm $$^{-2}$$ ). The lattice thermal conductivity of the buckled CSe sheet is in the range of 11.62 to 5.00 W m $$^{-1}$$ K $$^{-1}$$ , and the dimensionless figure of merit of n-type (p-type) CSe sheet is as high as 0.69 to 0.85 (0.18 to 0.40) at the temperatures from 300 to 700 K by choosing appropriate doping level. The high thermoelectric performance indicates that the buckled hexagonal CSe sheet is a promising n-type two-dimensional thermoelectric material.