Thermoelectric properties of doped β-InSe by Bi: First principle calculations

Abstract

The thermoelectric properties are investigated for doped β-InSe alloy with Bi on Se site (β-InSe1-xBix; x = 0.0, 0.0625, 0.125, 0.1875, 0.25). The calculations are based on density functional theory (DFT) combined with the Boltzmann transport theory. The calculated formation energies and elastic constants confirmed the thermodynamic and mechanical stability of their crystal structure. A direct band gap of 0.73 eV is predicted for β-InSe, however, the structure becomes metallic upon doping with Bi. The increase of Bi concentration leads to an enhancement in the power factor. The calculated lattice thermal conductivity (κL) and the figure of merit (ZT) of β-InSe are in excellent agreement with the reported experimental results. The κL value is decreasing as a result of doping, which reduces to about 50% in the case of β-InSe0.75Bi0.25from that of β-InSe at 300 K. This leads to an enhancement in the ZT value to 0.65 at 800 K.