We performed first-principles calculations based on density functional theory and many-body perturbation theory to investigate the electronic and optical properties of monolayer, bilayer, and bulk litharge α-PbO, including spin–orbit coupling effects. The fundamental gap is direct for the monolayer (4.48 eV) and indirect for the bilayer (3.44 eV) and the bulk material (2.45 eV). The exciton binding energies are large for the monolayer (1.1 eV) and the bilayer (0.9 eV), indicating that excitons are stable at room temperature. However, the lowest-energy excitons for the monolayer and the bilayer are dark with radiative lifetimes on the order of milliseconds. A pronounced van Hove singularity in the valence band of the few-layer structures suggests it becomes a multiferroic two-dimensional material upon hole doping. Our results indicate strong optical absorbance in the vacuum UV region and transparency in the visible and near UV for monolayer PbO, suggesting applications for atomically thin solar-blind UV photodetectors.

中文翻译：

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基于第一性原理的二维α-PbO的电子和光学性质

我们基于密度泛函理论和多体扰动理论进行了第一性原理计算，以研究单层，双层和块状α-PbO的电子和光学性质，包括自旋-轨道耦合效应。对于单层（4.48 eV），基本间隙是直接的；对于双层（3.44 eV）和本体材料（2.45 eV），基本间隙是间接的。对于单层（1.1eV）和双层（0.9eV），激子结合能大，表明激子在室温下是稳定的。但是，单层和双层的最低能量激子是暗的，辐射寿命约为毫秒。几层结构的价带中明显的van Hove奇异性表明，在空穴掺杂后，它成为多铁性二维材料。