Thermoelectric Properties of a Monolayer Bismuth

The structural and electronic properties of a two-dimensional monolayer bismuth are studied using density functional calculations. It is found that the monolayer forms a stable low-buckled hexagonal structure, which is reminiscent of silicene. The electronic transport properties of the monolayer bismuth are then evaluated by using Boltzmann theory with the relaxation time approximation. By fitting first-principles total energy calculations, a modified Morse potential is constructed, which is used to predicate the lattice thermal conductivity via equilibrium molecular dynamics simulations. The room temperature ZT value of a monolayer bismuth is estimated to be 2.1 and 2.4 for the n- and p-type doping, respectively. Moreover, the temperature dependence of ZT is investigated and a maximum value of 4.1 can be achieved at 500 K.