First-Principles Calculation of Optoelectronic Properties of Antimony Sulfides Thin Film

Antimony sulfide (Sb2S3) thin film have received great interests as an absorbing layer for solar cell technology. Electronic and optical properties of Sb2S3 thin films were studied by first principles approach. Highly accurate full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT) as implemented in WIEN2k package. The simulated film is in the [001] direction using supercell method with a vacuum along z-direction so that slab and periodic images can be treated independently. The calculated values of indirect band gaps of Sb2S3 for various slabs were found to be 0.568, 0.596 and 0.609 eV for 1, 2 and 4 slabs respectively. This trend is consistent with the experimental work where the band gap reduced when the thickness increased. Optical properties comprising of real and imaginary parts of complex dielectric function, absorption coefficient, refractive index was also investigated to understand the optical behavior of Sb2S3 thin films. From analysis of optical properties, it is clearly shown that Sb2S3 thin films have good optical absorption in the visible light and ultraviolet wavelengths, it is anticipated that these films can be used as an absorbing layer for solar cell and optoelectronic devices.