Materials and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
Nano Lett. 2023 May 24;23(10):4274-4281. doi: 10.1021/acs.nanolett.3c00386. Epub 2023 May 9.
The intrinsic weak and highly nonlocal dielectric screening of two-dimensional materials is well-known to lead to high sensitivity of their optoelectronic properties to environment. Less studied theoretically is the role of free carriers in those properties. Here, we use ab initio GW and Bethe-Salpeter equation calculations, with a rigorous treatment of dynamical screening and local-field effects, to study the doping dependence of the quasiparticle and optical properties of a monolayer transition-metal dichalcogenide, 2H MoTe. We predict a quasiparticle band gap renormalization of several hundreds of meV for experimentally attainable carrier densities and a similarly sizable decrease in the exciton binding energy. This results in an almost constant excitation energy for the lowest-energy exciton resonance with an increasing doping density. Using a newly developed and generally applicable plasmon-pole model and a self-consistent solution of the Bethe-Salpeter equation, we reveal the importance of accurately capturing both dynamical and local-field effects to understand detailed photoluminescence measurements.
二维材料本征的弱和高度非局域介电屏蔽众所周知会导致其光电性质对环境非常敏感。理论上研究较少的是自由载流子在这些性质中的作用。在这里，我们使用从头算 GW 和 Bethe-Salpeter 方程计算，以及对动态屏蔽和局域场效应的严格处理，来研究单层过渡金属二卤代物 2H MoTe 的准粒子和光学性质的掺杂依赖性。我们预测对于实验上可达到的载流子密度，准粒子带隙的重整化约为几百毫电子伏特，激子结合能也会有类似的大幅度降低。这导致随着掺杂密度的增加，最低能量激子共振的激发能量几乎保持不变。使用新开发的和普遍适用的等离子体极点模型以及 Bethe-Salpeter 方程的自洽解，我们揭示了准确捕捉动态和局域场效应以理解详细光致发光测量的重要性。
