Bandgap tuning in MoSSe bilayers: synergistic effects of dipole moment and interlayer distance

Abstract

From first principles calculations, the lowest energy structures of bilayer MoSSe with different combination patterns (S-S, Se-Se, and S-Se bilayers) have been confirmed. The results demonstrate that the band gap of bilayer MoSSe can be tuned by interlayer distance and dipole moment. A larger interlayer distance increases the band gap, while a larger dipole moment reduces the band gap. That is, the gap is affected by the synergistic effects of dipole moment and interlayer distance in a MoSSe bilayer. Our results provide a new way to realize band gap modulation by changing the dipole moment or the interlayer distance. Impressively, another important finding is that the S-Se bilayer has a type-II band alignment, which makes it a good candidate for applications in optoelectronics.

Rolling the WSSe Bilayer into Double-Walled Nanotube for the Enhanced Photocatalytic Water-Splitting Performance

“…According to Yang's findings above, it is believable that, if there are some method that could increase the surface potential difference and decrease the band gap for the 2D polar photocatalysts, their redox capacity and light absorption could be enhanced at the same time. For the recently emerged Janus MoSSe layered materials, it has been theoretically predicted that, stacking the monolayers to form bilayers could effectively narrow the band gap [11,12], causing a reinforced optical absorption, which is similar to the cases of C 3 N 4 and PtSSe [13,14]. In the meantime, the dipole moment of Janus MoSSe layered materials, which is represented by the plane electrostatic potential difference between the two surfaces, has been found to almost linearly increase with the growing thickness [11,12,15].…”

“…For the recently emerged Janus MoSSe layered materials, it has been theoretically predicted that, stacking the monolayers to form bilayers could effectively narrow the band gap [11,12], causing a reinforced optical absorption, which is similar to the cases of C 3 N 4 and PtSSe [13,14]. In the meantime, the dipole moment of Janus MoSSe layered materials, which is represented by the plane electrostatic potential difference between the two surfaces, has been found to almost linearly increase with the growing thickness [11,12,15]. Furthermore, the observed type-II band alignment in the Janus MoSSe bilayers could suppress the recombination of photo-excited carriers for the thorough-going spatial separation [16].…”

Intriguing electronic structure and photocatalytic performance of blueP–SMSe and blueP–SeMS (M = Mo, W) van der Waals heterostructures

“…14 Janus XMY monolayers have an asymmetric structure, and exhibit a direct semiconducting band gap nature, giant Rashba spin splitting, exciting optoelectronic properties and photocatalysis of water. [15][16][17][18] Blue phosphorus (blueP) and black phosphorus (blackP) with buckled honeycomb lattice symmetry have also been theoretically demonstrated as new 2D allotropes of phosphorous poly-types. [19][20][21][22] Zhang et al 23 have successfully synthesized single layer blueP on an Au(111) substrate using molecular beam epitaxy technique.…”

Electro-optical effect of the nCOOCB liquid crystal molecules under the terahertz frequency range: A theoretical approach

“…Shang et al have reported the dipole moment, and energy bandgap are inversely proportional to each other. 30 In the present work, the dipole moment is inversely proportional to each other because it increases for the even members and the Homo-Lumo gap increases for the odd members.…”