Influence of Sulfur Defects on the Electronic and Optical Properties of Torsional NbS2: First‐Principles Calculation

For single‐layer NbS 2 , the effect of torsional deformation on the electronic structure of defect NbS 2 is studied by first principles. The electronic structure changes caused by two defect states are recorded: energy band, bond length, defect formation energy, electronic state density, and differential charge density. Single‐air sulfur defect V S and double‐air sulfur defect V 2S are studied. Based on the two states, the defect system is twisted. The results show that the indirect bandgap of NbS 2 is successfully induced by twisting the defect system, and the single‐layer NbS 2 is transited into a diluted semiconductor. At the same time, the electronic characteristics can be controlled regularly. On the other hand, the hybrid system can significantly improve the absorption coefficient and transmittance of single‐layer NbS 2 in the visible light region, promote the reflection of ultraviolet light, and effectively improve the optical response and photocatalytic activity in the low‐energy region. The results herein lay a foundation for the flexible application of 1T‐NbS 2 according to its electronic and optical properties.