A comparative study of thermoelectric properties of monolayer, bilayer and bulk CrI3

We comparatively study the electronic and thermoelectric properties of the monolayer, bilayer, and bulk CrI3 by density functional theory (DFT). We show that, according to the DFT calculation, those materials are magnetic semiconductors with ferromagnetic (FM) in monolayer, antiferromagnetic (AFM) in the bilayer, back to FM in the bulk structure. The thermoelectric properties of those materials are evaluated by using the Boltzmann transport equation (BTE) with a constant relaxation time approximation (RTA). At room temperature, we obtain bulk CrI3 has more significant electrical conductivity than monolayer and bilayer CrI3, while the Seebeck coefficient is similar that implied the bulk CrI3 has a better thermoelectric performance. In those systems, the optimum power factor is obtained by shifting the chemical potential of CrI3 by 1 eV with p-type doping.