Influence of Janus structure on the thermoelectric performance of the <i>α</i>-Se monolayer

Aiming at exploring whether the Janus structure is beneficial to improving the thermoelectric (TE) performance, we systematically study the TE properties of the α-Se-monolayer-based Janus structures including α-SSe2 and α-TeSe2 monolayers. In comparison with the semiconducting α-Se monolayer, the Janus α-SSe2 and α-TeSe2 monolayers are still kept to be indirect semiconductors but with suppressed energy bandgaps. Moreover, the phononic thermal conductance will be suppressed with other parameters like Seebeck coefficients, electrical conductances, and electronic thermal conductances being changed correspondingly. The TE figures of merit ZTs of the Janus α-SSe2 and α-TeSe2 monolayers are always greater than that of the α-Se monolayer, indicating that the Janus structure should be a potential scheme used to improve the TE performance of materials.