A theoretical benchmark for the electronic, optical, and thermoelectrical characteristics of bulk and monolayer BiS2

The electronic, optical, and thermoelectrical characteristics of bulk BiS2 (b-BiS2) and monolayer BiS2 (ml-BiS2) were analyzed and benchmarked using density functional theory (DFT) calculations. Both the ml-BiS2 and b-BiS2 structures display indirect bandgaps, where ml-BiS2 has a bandgap of 1.59 eV, which is slightly larger than that of b-BiS2 (1.51 eV). According to the presently revealed optical parameters, both counterparts of the BiS2 compound exhibit high dielectric properties, ideal photoconductivity, high refractivity, and efficient absorptivity, especially for convenient applications in the ultraviolet (UV) zone. Furthermore, the obtained phonon dispersions with positive frequencies suggest obvious dynamic stability behavior for both b-BiS2 and ml-BiS2. Finally, b-BiS2 with a Seebeck coefficient of 2300 μV/K and a figure of merit (ZT) of 0.99 and ml-BiS2 with a Seebeck coefficient of 2584 μV/K and ZT = 1 at room temperature (300 K) are promising novel p-type thermoelectric materials for the future energy industry and technology.