g-CN体系的准粒子能带结构和光学特性（英文）

发布时间：2018-03-24 01:23

  本文选题：g-CN　切入点：准粒子能带结构　出处：《物理化学学报》2016年08期

【摘要】：利用多体格林函数理论,本文研究了二维CN体系(包括triazine和tri-s-triazine)的激发态特性。通过GW方法,我们计算了准粒子的能量。考虑电子-空穴相互作用,通过求解Bethe-Salpeter方程,我们获得了激发态能量和光谱。我们发现,在这两种CN体系的价带中,σ轨道和π轨道之间的交换作用非常强烈。由于占据的σ轨道和π轨道之间的准粒子修正量非常不同,因此,为了得到准确的带隙值和光谱,我们需要对这两种轨道开展精确的GW计算。与单层的CN体系相比,双层结构中层与层之间的范德华相互作用使带隙值降低了0.6 e V,而光吸收谱红移了0.2 e V,这是由于双层结构具有更小的激子束缚能。我们计算的吸收峰的位置与实验结果符合很好。实验中的吸收峰主要是由深能级的π轨道到π*轨道的跃迁形成的。π→π*跃迁和σ→π*跃迁之间的耦合能够在长波长范围产生弱的吸收尾巴,如果调整入射光的极化方向,由σ→π*跃迁产生的高强度的吸收峰将会在更低能量处出现。
[Abstract]:In this paper, the excited state properties of two-dimensional CN system (including triazine and tri-s-triazine) are studied by using the theory of multibody Green's function. By GW method, the energy of quasiparticle is calculated. Considering the electron-hole interaction, the Bethe-Salpeter equation is solved. We have obtained the excited state energy and spectra. We find that the exchange between 蟽 orbital and 蟺 orbital is very strong in the valence band of these two CN systems, because the quasiparticle correction between the occupied 蟽 orbital and 蟺 orbital is very different. Therefore, in order to obtain accurate band gap value and spectrum, we need to carry out accurate GW calculations for these two orbits. The van der Waals interaction between the bilayer structure and the middle layer reduces the band gap by 0.6 EV, while the absorption spectrum redshifts by 0.2 EV, which is due to the smaller exciton binding energy of the bilayer structure. The experimental results are in good agreement. The absorption peak in the experiment is mainly formed by the transition from the deep level 蟺 orbital to the 蟺 * orbital. 鈫捪，

本文编号：1656089