Enhanced thermoelectric performance of twisted bilayer blue phosphorene

Abstract

Aiming at exploring the feasibility of improving the thermoelectric (TE) performance by twist in blue phosphorene systems, we make a systematic investigation into the TE properties of the twisted bilayer blue phosphorene (tbBP). By comparing the Seebeck coefficients, electrical conductances, power factors, thermal conductances, and figures of merit ZTs of six tbBPs with different twist angles, we can find that the maximum ZT of the tbBP can be enhanced by changing the twist angle, which provides a degree of freedom to manipulate the TE performance. In comparison with the 60^∘ tbBP (the usual bilayer blue phosphorene), the maximum ZT of the 9.4^∘ tbBP can be enhanced by 7 (14) times along the armchair (zigzag) direction at the temperature of 300 K. In addition, we show that the ZT peak value will be further increased as the temperature increases. At the high temperature of 900 K, the ZTs of the 9.4^∘ tbBP along the zigzag and armchair directions may be greater than 3, indicating that the tbBPs can be used as high-performance TE materials. Our findings point to an opportunity to improve the ZT by means of the twisting scheme.