Insights Into the Infrared Optical Properties of Janus WSSe Monolayer Doped With Pb, Pt, and Hg Based on the First Principles

Abstract This study systematically investigates the infrared optical properties of 2D Janus WSSe monolayers doped with Pb, Pt, and Hg using first principles calculations. By constructing supercell models with different doping concentrations (4%, 6.25%, 11.11%), the regulatory mechanisms of doping on electronic structures (band structures, density of states) and optical properties (absorption coefficients) are analyzed. The results show that doping significantly enhances infrared absorption performance. Specifically, Hg doping at 11.11% concentration achieves the highest absorption peak at 0.63 eV (αmax = 8.8 × 10⁴ cm⁻¹), Pt doping forms a single strong absorption peak at 0.87 eV at 11.11% and Pb doping exhibits dual absorption peaks at 0.67 eV and 1.44 eV at 11.11%. Doping elements alter the band structure through orbital hybridization (e.g., Hg‐d/Se‐p, Pt‐d/W‐d, Pb‐p/W‐d). Hg doping leads to a bandgap type transition (direct → indirect) at high concentrations, while Pt and Pb doping maintain a direct bandgap. This research reveals the collaborative regulation of infrared absorption by doping elements and concentrations providing a theoretical basis for designing efficient infrared optoelectronic devices.