Ab initio prediction of thermoelectric performance of monolayer BiSbTe3

Abstract

The transport properties on the monolayer BiSbTe3 were studied by density functional theory and Semi-classical Boltzmann Transport equation. For monolayer BiSbTe3, the band gap with TB-mBJ can be improved for monolayer BiSbTe3 comparing with GGA. There is no imaginary frequency for the phonon band structure of monolayer BiSbTe3, which guarantees its dynamic stability. The heavy elements and small band gap between the acoustic mode and the optical mode causes lower lattice thermal conductivity for monolayer BiSbTe3. Due to the flat valence band near Fermi level, p-type doping produces higher S values than n-type doping. The monolayer BiSbTe3 with TB-mBJ can’t improve electrical conductivities, but TB-mBJ can reduce the electronic thermal conductivity. Compared with other well-known two-dimensional materials, monolayer BiSbTe3 have larger ZT. ZT of monolayer BiSbTe3 with n ​= ​1020 ​cm−3 calculated by GGA is 1.002 ​at 900 ​K.