Tuning the Optical Properties of Zinc Sulfide Nanotube

Optical properties of zinc sulfide (ZnS) nanotube (NT) are tuned by changing its chirality and adsorbing phosphorous. It is found that Armchair (4, 4) ZnS NT results in largest absorption coefficient in ultraviolet region in comparison to zigzag and chiral ZnS NTS. Zigzag (5, 0), (6, 0) and chiral (4, 2) ZnS NTS have larger bandgap and lower absorption in comparison to armchair (3, 3), (4, 4), and (5, 5) ZnS NTs. On changing the chirality of armchair ZnS NTS from (3, 3) to (4, 4) and then to (5, 5), it is found that absorption can be tuned to higher values in an ultraviolet region in the case of (4, 4) NTS which has a higher absorption coefficient in ultraviolet region than (3, 3) and (5, 5) NTS. The absorption in armchair ZnS NTs can be tuned to increase with increase in nanotube bandgap and can also be tuned to increase with decrease in bandgap in ziz-zag NTs. Furthermore, adsorption of phosphorous over ZnS NT results in lower formation energies, thus making it more stable. The magnitude of absorption coefficient peak reduces in the ultraviolet region, and the absorption peaks spread over infrared and visible regions as well in phosphorous-adsorbed NTs.