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.

中文翻译：

---

2D五-PdX2单层的超高载流子迁移率和光捕获性能

在这项研究中，我们使用密度函数计算检查了五-PdX2 (X = As,P) 的几何、电子和光学特性。电子结构计算表明，penta-PdAs2 和 PdP2 是直接带隙分别为 0.34 eV 和 0.30 eV 的半导体。声子色散曲线中没有虚频率证明了五-PdX2 单层的动力学稳定性。通过在单层上应用双轴应变（对于 PdAs2：- 6% 到 + 6%，对于 PdP2：- 5.5% 到 + 5.5%），有效质量和带边缘被有效地调整。值得注意的是，五-PdX2 载流子迁移率的范围非常高，空穴为 105 cm2 V-1 s-1，电子为 104 cm2 V-1 s-1。penta-PdX2 的光学特性也是应变可调的，并表现出出色的红外吸收，可见光和紫外线。更重要的是，带边缘对齐可通过沿 z 方向实施的外部电场 (V/Å) 进行调整。我们的工作将刺激五-PdX2 单层的制造，预计它是未来光电和超快电子应用的合适候选者。