First-principles investigation of transition-metal (Cu, Zn, Fe, Sc, V) doped monolayer SnSe: Electronic structures and optical properties

Based on first-principles calculations within the framework of density functional theory, this work systematically investigates the electronic structures and optical properties of monolayer α-SnSe and its five transition-metal-doped systems (Cu, Zn, Fe, Sc, and V), aiming to reveal the physical mechanisms underlying the synergistic regulation of multiple material properties by doping. The results indicate that Sc and V doping both drive the system from an indirect to a direct bandgap, thereby facilitating carrier excitation and transport. Specifically, Sc doping reduces the bandgap from 1.082 eV to 0.998 eV and exhibits the lowest work function (2.78 eV), significantly enhancing electronic transition capability and interfacial electrode response efficiency. Regarding optical properties, all five doped systems display a redshift in the visible region, with Cu doping showing the most pronounced shift (≈3.1 eV) and exhibiting stronger low-energy absorption peaks, demonstrating excellent photoelectric performance. In addition, Cu and V doping enhance the polarization response of the material, improving its charge regulation ability under external electric fields. In summary, transition-metal doping can influence α-SnSe in multiple dimensions, including its electronic structure and optical properties, thereby synergistically enhancing its optoelectronic properties and electronic tunability. This provides theoretical support and design guidance for its potential applications in novel optoelectronic conversion and capacitor devices. Transition-Metal Doping Modulates Work Function and Optical Response in Monolayer α-SnSe