High Anisotropic Optoelectronics in Two Dimensional Layered PbSnX₂ (X = S/Se)

Abstract

We systematically study the giant anisotropic optoelectronics in layered PbSnX2 (X = S/Se). The highly anisotropic optoelectronics mainly originates from the asymmetric sublattices SnX, resulting in the anisotropy of photoelectronic properties with fascinating visible light absorption range in single-layer and bilayer PbSnX2. We employ uniaxial strain in both the x and y directions and find an indirect-to-direct band gap transition, while the quasiparticle indirect band gap presents excellent linear scaling with biaxial strain in monolayer PbSnX2. We also demonstrate ultrahigh anisotropic mobilities of electrons (μ y > μ x ) and holes (μ x > μ y ) in both single-layer and bilayer PbSnX2 (X = S/Se), and spin–orbit coupling effects and the increase of layer number significantly reduce exciton binding energies and band gaps. Finally, the strong layer dependence of the band structure is clearly seen when the film thickness is less than 4 layers. Our results provide a fundamental understanding of highly anisotropic PbSnX2 (X = S/Se) and show two potential candidates in photoelectric applications.

Charge transport mechanisms of PbSnSe2 and observation of transition from direct to Fowler–Nordheim tunneling

“…1b , the flake exhibits semiconducting behaviors. Xu et al 10 have shown that PbSnSe 2 exhibits semiconducting behaviors if the number of layers in the flake is less than 8. Therefore, we suggest that the number of layers in the flake should be less than 8.…”

“…2d shows that the value of the dielectric constant for PbSnSe 2 in the temperature range of 150 K–220 K is approximately 1.4, which is much close to the values of the dielectric constant found for the ternary compound. 10 …”

“…9 PbSnSe 2 is a ternary compound of group IV metal chalcogenides poised to unravel new paradigms in the field of nanoelectronics. Only a few computational studies have been reported on this material; 10–12 however, experimental studies on PbSnSe 2 have been overlooked.…”

Giant In-Plane Flexoelectricity and Radial Polarization in Janus IV–VI Monolayers and Nanotubes

“…These and other fascinating properties drive the interest of the community to search for more compositions and crystal structures that can form Janus 1D nanotubes with small radii and novel properties arising from the spontaneous wrapping of the 2D sheet into a tube. The class of 2D group IV–IV monochalcogenides (as illustrated in Figure a) show strong mechanical and electronic anisotropy and giant in-plane spontaneous polarization, ,, and have properties interesting for electronic and optoelectronic applications, Their Janus form, e.g., PbSnS 2 , has recently emerged and brought new perspectives for electronic, thermoelectric, supercapacitors, and optoelectronics devices. − …”

High hole mobilities in two dimensional monolayer MSi2Z4 (M = Mo/W; Z = P, As, Sb) for solar cells

“…Recent experimental evidence suggests that ultrathin (2.4 nm) PbSnS 2 sheets possess not only a large anisotropic photoresponse but also highly anisotropic hole mobility synthesized by the chemical vapor deposition (CVD) method. 27,28 Furthermore, the synthesized layered SnP 2 S 6 exhibits excellent photosensitive capabilities in addition to its rich piezoelectric properties and ionic conductivity. 29,30 It has been investigated that the synthesized ternary compounds exhibit not only a favorable band gap and carrier mobility but also high stability, and their variable stoichiometric ratios lead to the construction of abundant 2D optoelectronic materials.…”