First principles calculations of the density of states and the optical absorption coefficients of W-doped SnS2

Abstract

First principles calculations of the electronic density of state (DOS) and the optical absorption coefficient of SnS2, Sn0.875W0.125S2 and Sn0.75W0.25S2 are presented using the PBE-GGA formalism and the TBmBJ potential. The band gap of SnS2 is found to be 2.1 eV when the TBmBJ potential is used. This value is in excellent agreement with reported experiments. Doping the parent tin disulfide (SnS2) by W atoms is found to produce intermediate bands (IB) in the vicinity of the Fermi level. The calculated optical absorption coefficient is seen to enhance and cover a wide range of energy extending from the infrared red region up to the ultraviolet region irrespective of the type of exchange functional or potential. From the DOS results, the role of the TBmBJ potential is found to correct the values of the band gap and place the IB in the correct position. Consequently, this affects the dependence of the optical absorption coefficient on the energy. Furthermore, it reveals the occurrence of additional optical processes. Our findings support the use of the W-doped SnS2 compounds as intermediate band materials in solar cells applications.