Tuning the Electronic and Thermoelectric Properties of Selenium Monolayers Through Atomic Impurities: A DFT Study

The structural, electronic, and thermoelectric properties of selenium monolayer with impurity adsorption and substitutional atoms have been studied using density functional theory (DFT) combined with semiclassical Boltzmann theory. The adsorption energy of the impurity adatoms in their stable position ranged from −1.46 eV for Te to −4 .44 eV for Pt. Regarding the atomic substitution, Pt impurities exhibited the highest stability in the intermediate position, with a formation energy of −150.5 meV, followed by Sn with a formation energy of −90.40 meV. We further investigated the impact of atomic impurities on the electronic properties of the material and found that the bandgap energy was significantly reduced, resulting in a semiconductor-to-metal transition. These results highlight the effectiveness of defect engineering for electronic band tuning. Furthermore, we discovered that a selenium monolayer with substitution of an Sn or Te atom in the intermediate layer exhibits a maximum value of the dimensionless figure of merit (including electronic and phononic contributions) of 0.51 and 0.52, respectively, while the clean selenium monolayer has a maximum value of ZT=0.43. These finding suggest that selenium monolayer with Sn defects could be a promising thermoelectric materials that offer an alternative for recovering waste heat and transforming it into electricity.