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.