Effect of sulfur dopant atoms on the electronic band gap and optical properties of tin iodide.

• Both SnI 2 and Sn 4 SI 6 have the layer crystal structure. • The crystal structure of Sn 4 SI 6 is equivalent to that of SnI 2 doped with S atoms. • The sulfur dopant atoms can affect the electronic band gap. • The positions of the optical peaks can be affected via doping by sulfur atoms. Layered luminescence semiconductors SnI 2 and Sn 4 SI 6 have been employed in electronic discharge lamps, photo-recording medium, and other applications, owing to their high color rendering index and high photosensitivity. The crystalline, electronic and optical properties of these two compounds were investigated by the density functional theory. The results indicate that the sulfur dopant atoms have a small effect on the profiles of the electronic band structure and optical curves. However, sulfur doping changes the electronic band gap, the positions of the absorption edge, and the dielectric and absorption peaks. These results support the further study and application of these two compounds. [ABSTRACT FROM AUTHOR]