Defect states and defect-induced phase transition in bent transition metal dichalcogenide (TMD) nanoribbons and excitonic states

Two-dimensional (2D) transition metal dichalcogenide (TMD) materials have versatile electronic and optical properties. TMD nanoribbons show interesting properties due to reduced dimensionality, quantum confinement, and edge states. Tang et al. [1] showed that the edge bands evolved with bending can tune the optical properties for various widths of TMD nanoribbons. Defects are commonly present in 2D TMD materials, and can dramatically change the material properties. In this following work, we investigate the interaction between the edge states and the defect states in WS₂ nanoribbons with line defects under different bending conditions, using the r²SCAN meta-GGA density functional [2]. We reveal interesting semiconducting-to-metallic phase transitions, suggesting potential applications in nano-electronics or molecular electronics. We also calculate the optical absorption of the nanoribbons with different defect positions with the many-body GW-BSE (Bethe-Salpeter equation) approach, revealing the tunable optical spectrum and diverse exciton states in the defected TMD nanoribbons.

[1] Tang, H., Neupane, B., Neupane, S., Ruan, S., Nepal, N.K., and Ruzsinszky, A., Sci Rep 12, 3008 (2022)

[2] Furness, J.W., Kaplan, A.D., Ning, J., Perdew, J.P. and Sun, J., J. Phys. Chem. Lett. 11, 8208 (2020)