Computational study of antimony sulphide absorbance layer for solar cells

Abstract

The demand for cheaper, nontoxic and earth-abundant materials as absorbing layer for solar cell is immensely needed to replace scarce, toxic and expensive one. In this regard, chalcogenide materials have attracted the attention of a lot of researchers because of their great potential in different applications. Antimony sulphide (Sb2S3), a chalcogenide binary material is investigated to exploit its potential for different energy technologies being a less toxic, abundantly available, stable and efficient, which are the fundamentals for sustainability as well as to realize the dream of green energy. Theoretical calculations based on density functional theory (DFT) are employed to study and understand the structural, electronic and optical properties of Sb2S3 for threedimensional (3-D), two-dimensional (2-D) and one-dimensional (1-D) structures. Here, the investigations have been performed by full-potential linearized augmented plane-wave method (FP-LAPW) within the WIEN2k computational code. The optical properties such as imaginary and real parts of the dielectric function, absorption coefficient, refractive index, reflectivity, and electron energy loss function are analyzed. In 3-D structure study, lattice parameters obtained are comparable to the experimental measurements. The obtained indirect energy band gap of 1.63 eV and optical properties are also closer to the experimental data. As the dimensions and size changed, the physical properties of Sb2S3 are also changed. The indirect energy band gaps obtained for 2-D and 1-D structures of Sb2S3 are 0.57 eV and 0.12 eV, respectively which are smaller than 3-D Sb2S3. The investigation of thickness effect on 2-D Sb2S3 is presented. The obtained values of indirect energy band gaps for various levels were found to be 0.568, 0.596 and 0.609 eV for 1, 2 and 4 levels, respectively. The density of state (DOS) illustrated for both 2-D and 1-D structures are higher than 3-D structure. The obtained absorption coefficients for both Sb2S3 structures are around 104 cm-1 in the visible light and ultraviolet regions. The static refractive index calculated for 3-D, 2-D and 1-D structures are 3.05, 1.77 and 1.48, respectively. From these results, it is clearly shown that 2-D and 1-D Sb2S3 structures have lower optical properties than 3-D Sb2S3. However, the absorption coefficients of 2-D and 1-D Sb2S3 structures are considerably higher and reflect their potentiality for photovoltaic applications.