Monolayer PtSe₂, a New Semiconducting Transition-Metal-Dichalcogenide, Epitaxially Grown by Direct Selenization of Pt

Abstract

Single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. A combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrast to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.

Strain-Modulated Electronic Structure and Infrared Light Adsorption in Palladium Diselenide Monolayer

“…The Pd-Se bond length is about 2.528 Å. The optimized lattice constant of the hexagonal lattice is 3.739 Å, quite close to that of the PtSe 2 monolayer, 3.7 Å 9. Notably, a 3 × 3 PdSe 2 monolayer (11.217 Å) matches well with the 4 × 4 Pd(111) surface (11.186 Å), which implies high plausibility of growing PdSe 2 monolayer on Pd(111) surface via selenization.…”

“…The latter case has orthorhombic symmetry with four-coordinated Pt atoms and two-coordinated Se atoms, and is slightly stable than the hexagonal structure by about 26 meV/atom. However, the hexagonal PdSe 2 monolayer matches well with the Pd(111) surface in both symmetry and lattice constant along with a negative binding energy (−1.04 eV per PdSe 2 unit) and thus has high plausibility on the Pd(111) surface as the surface is selenized9.…”

“…The PBE functional underestimated the band gap value (0.7 eV) compared with HSE functional (1.10 eV). The band gap of PdSe 2 monolayer is slightly smaller than that of PtSe 2 monolayer (1.2 eV)9 and orthorhombic PdSe 2 (1.43 eV)11 and suitable for adsorbing infrared light. From the orbital-resolved electron density of states shown in Fig.…”

“…So far, theoretical and experimental efforts have been mainly focused on semiconducting 2D-TMDs with M = Mo and W1234, due to potential applications in terahertz switch5, lasers and LEDs6, ambipolar ionic liquid gated field-effect transistor7, photo detectors1, and so on8. In a recent work9, PtSe 2 monolayer was synthesized via a single step of direct selenization of a Pt(111) substrate and demonstrated to have potential application as valleytronics and photocatalyst.…”

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2

“…Molecular beam epitaxy (MBE) has recently been adopted to synthesize atomically thin transition metal dichalcogenides (TMDs) 21,[29][30][31][32][33] . With certain procedures, networklike inversion domain boundaries (IDBs) were introduced into MoSe2 monolayers, behaving as metallic mid-gap states with signature for undergoing charge density wave transition at low temperature 29,34 .…”