Ab Initio Electronic and Thermoelectric Calculations of Atomically Thick Nanofilms

A comparative investigation on electronic and thermoelectric (TE) properties of Sb 2 Te 3 , Bi 2 Se 3 , BiSbSe 3 , and BiSbTe 3 monolayers is carried out using first principle calculation and Boltzmann transport theory. The density functional theory calculations are performed by adopting Perdew–Burke–Ernzerhof (for solids) generalized gradient approximation (GGA‐PBEsol) as exchange‐correlation functional. The calculation of electronic properties of the atomically thick materials reveals all to be of indirect bandgap type with BiSbSe 3 and BiSbTe 3 having narrowest and widest bandgaps, respectively. All the monolayers show Mexican hat dispersion in the valence bands. The phonon dispersion confirms the dynamic stability of the monolayers. Further examination of electronic properties is carried out by calculating total and partial density of states. The TE properties of these 1‐quintuple (QL) layer materials are calculated using semi‐classical Boltzmann transport theory and rigid band approximation together with the electronic properties derived from first principles. The Sb 2 Te 3 QL shows highest power factor (relative to relaxation time) of 3.1 × 10 11 WK −2 m −1 s −1 among others. The figure of merit (ZT) of these TE materials is also calculated with a highest value of 0.99 obtained for Sb 2 Te 3 monolayer. The BiSbSe 3 monolayer lacks behind in giving good TE performance due to dominating bipolar conduction effect.