Electronic and optical properties of a novel two-dimensional semiconductor material TlPt₂S₃: a first-principles study

Two-dimensional (2D) materials have attracted widespread attention due to their unique physical and chemical properties. Here, by using density functional theory calculations, we suggest a novel 2D TlPt₂S₃ material whose layered bulk counterpart was synthesized in 1973. Theoretical calculation results indicate that the exfoliating energy of monolayer and bilayer TlPt₂S₃ is 34.96 meV Å^-2 and 36.03 meV Å^-2. We systematically studied the electronic and optical properties of monolayer and bilayer TlPt₂S₃, and revealed that they are indirect band gap semiconductors with band gaps of 2.26 eV and 2.10 eV, respectively. Monolayer and bilayer TlPt₂S₃ exhibit superior carrier mobility (901.63 cm² V^-1 s^-1 and 13635.04 cm² V^-1 s^-1 for electron mobility of the monolayer and bilayer, respectively) and photocatalytic performance (as high as 1 × 10⁵ light absorption coefficient in the visible light region). Interestingly, we find that monolayer TlPt₂S₃ has significant hydrogen evolution performance, while in the bilayer, the electron band distribution shows complete oxygen evolution ability, which indicates that the proposed monolayer and bilayer TlPt₂S₃ are potential novel 2D materials suitable for photocatalytic water splitting driven by visible light.