Probing Multiphased Transition in Bulk MoS₂ by Direct Electron Injection

Abstract

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 MoS2 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 MoS2 using MoS2/[Ca2N]+·e– heterostructures, in which kinetic free electrons were directly injected into MoS2. We observed various phases in MoS2 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 MoS2. Our results thus suggest the optoelectronic applications that can fully utilize the multiphase transition of bulk 2D materials.

Doping-Mediated Lattice Engineering of Monolayer ReS2 for Modulating In-Plane Anisotropy of Optical and Transport Properties

“…As the treatment time increased, the softening and broadening of the Raman modes increased, indicating an increase in the electron density and electron−phonon coupling. 8,12,32,33 We note that each Raman frequency displayed slightly different amounts of red-shift because of the different origins of the vibrational modes. 12,32,33 The inplane mode at 212.8 cm −1 showed red-shifts of 1, 1.6, and 3.1 cm −1 with 3, 6, and 9 h Li treatment, respectively, as indicated by the dashed line in Figure 4a (see Table S2 for details on the softening of other modes).…”

“…8,12,32,33 We note that each Raman frequency displayed slightly different amounts of red-shift because of the different origins of the vibrational modes. 12,32,33 The inplane mode at 212.8 cm −1 showed red-shifts of 1, 1.6, and 3.1 cm −1 with 3, 6, and 9 h Li treatment, respectively, as indicated by the dashed line in Figure 4a (see Table S2 for details on the softening of other modes). By increasing the treatment time to 12 h, the Raman modes were distinctively quenched, which is attributed to the Pauli blocking induced by the high electron density.…”

Scalable lateral heterojunction by chemical doping of 2D TMD thin films

“…6 c that illustrates the band profiles and band alignment between the undoped MoS 2 and BV doped MoS 2 regions. The work function of the pristine MoS 2 has been reported to be in the range of 4.6–4.9 eV 61 – 64 . Although, the exact work function of BV doped MoS 2 is not known, we expect this to be lower than MoS 2 due to the increased carrier concentration by doping as the work function is known to be modulated by p or n-doping 5 , 65 .…”

Hydrogen Adsorption on the Vertical Heterostructures of Graphene and Two-Dimensional Electrides: A First-Principles Study

“… 13 The electron anion between the positively charged Y 2 C layers possesses more electrons than that in Ca 2 N. Kim et al combined 2D electrides with the layered material MoTe 2 . 14 The 2D electride [Ca 2 N] + ·e – diffuses electrons into MoTe 2 , producing an electron doping density in excess of 1.6 × 10 14 cm –2 and introducing changes in the lattice symmetry. Dhakal et al reported the 2H to 1T′ phase transition and intermediates in bulk MoS 2 by using MoS 2 /[Ca 2 N] + ·e – heterostructures.…”