The Near-Infrared-II Optical Tuning and Electronic Engineering of MoS2 Bilayers Doped by Halogen Elements

The improvement of optical absorption behavior of the second near-infrared region (NIR-II, 1000-1350 nm) based on new function materials is significant for the development of biomedicine and optical imaging. Therefore, the electronic structures and optical absorption of 2H phase MoS2 doped by F, Cl, Br, and I atoms with various doping concentrations are calculated, results show that halogen elements introduced extra transition allowed bands which is about 1.0 eV wide to 2H-MoS2, and the increasing of impurity concentration can trigger strong spin splits. The transformation of electronic structures leads to 2H-MoS2 metallic behaviors, improves transition efficiency, and lowers photon energy loss. More importantly, strong light-mass interaction is verified and breaks the energy level degeneracy, makes absorption peaks at 0.6-1.0 eV photon energy region, successfully extends the work region of 2H-MoS2 to NIR-II window, greatly improves the optical response and application potential in the photoelectric field. These results not only prove the potential of halogen elements as dopants in bandgap engineering of 2H-MoS2 but also may indicate a direction for seeking new generation function materials that own excellent performance in the NIR-II window, which is of great significance to promote the development of optoelectronics and bioimaging applications.