Probing Multiphased Transition in Bulk MoS by Direct Electron Injection.

Structural phase transitions in layered two-dimensional (2D) materials are of significant interest owing to their ability to exist in multiple metastable states with distinctive properties. However, phase transition in bulk MoS by nondestructive electron infusion has not yet been realized. In this study, we report the 2H to 1T' phase transition and in-between intermediates in bulk MoS using MoS/[CaN]·e heterostructures, in which kinetic free electrons were directly injected into MoS. We observed various phases in MoS ranging from heavily doped 2H to a distorted lattice state and then on to a complete 1T' state. Snapshots of the multiphase transition were captured by extraordinary Raman shift and bandgap reduction and were further elucidated by theoretical calculations. We also observed a weakening in interlayer coupling in the vicinity of the metallic regime, which led to an unusually strong photoluminescence emission, suggesting light-efficient bulk MoS. Our results thus suggest the optoelectronic applications that can fully utilize the multiphase transition of bulk 2D materials.