Ultrahigh carrier mobility and light-harvesting performance of 2D penta-PdX2 monolayer

In this study, we have examined the geometrical, electronic and optical properties of penta-PdX2 (X = As,P) using density functional calculation. The electronic structure calculations show that the penta-PdAs2 and PdP2 are semiconductors with direct band gaps of 0.34 eV and 0.30 eV, respectively. The dynamical stability of penta-PdX2 monolayer is proved by the absence of imaginary frequencies in the phonon dispersion curve. By applying a biaxial strain (for PdAs2: − 6% to + 6% and for PdP2: − 5.5% to + 5.5%) on the monolayer, the effective mass and band edges are tuned effectively. Remarkably, the range of penta-PdX2 carrier mobility was obtained in an extremely high order of 105 cm2 V−1 s−1 for holes and 104 cm2 V−1 s−1 for electrons. The optical properties of penta-PdX2 were also strained-tunable and exhibit outstanding absorption of infrared, visible and ultraviolet light. More importantly, the band edges alignment has tunable with implemented external electric field (V/Å) along the z-direction. Our work would stimulate the fabrication of penta-PdX2 monolayer, and it is envisioned that it is an appropriate future candidate for optoelectronic and ultra-fast electronic applications.