發(fā)布時(shí)間：2018-03-24 01:23

  本文選題：g-CN　切入點(diǎn)：準(zhǔn)粒子能帶結(jié)構(gòu)　出處：《物理化學(xué)學(xué)報(bào)》2016年08期

【摘要】：利用多體格林函數(shù)理論,本文研究了二維CN體系(包括triazine和tri-s-triazine)的激發(fā)態(tài)特性。通過(guò)GW方法,我們計(jì)算了準(zhǔn)粒子的能量�？紤]電子-空穴相互作用,通過(guò)求解Bethe-Salpeter方程,我們獲得了激發(fā)態(tài)能量和光譜。我們發(fā)現(xiàn),在這兩種CN體系的價(jià)帶中,σ軌道和π軌道之間的交換作用非常強(qiáng)烈。由于占據(jù)的σ軌道和π軌道之間的準(zhǔn)粒子修正量非常不同,因此,為了得到準(zhǔn)確的帶隙值和光譜,我們需要對(duì)這兩種軌道開(kāi)展精確的GW計(jì)算。與單層的CN體系相比,雙層結(jié)構(gòu)中層與層之間的范德華相互作用使帶隙值降低了0.6 e V,而光吸收譜紅移了0.2 e V,這是由于雙層結(jié)構(gòu)具有更小的激子束縛能。我們計(jì)算的吸收峰的位置與實(shí)驗(yàn)結(jié)果符合很好。實(shí)驗(yàn)中的吸收峰主要是由深能級(jí)的π軌道到π*軌道的躍遷形成的。π→π*躍遷和σ→π*躍遷之間的耦合能夠在長(zhǎng)波長(zhǎng)范圍產(chǎn)生弱的吸收尾巴,如果調(diào)整入射光的極化方向,由σ→π*躍遷產(chǎn)生的高強(qiáng)度的吸收峰將會(huì)在更低能量處出現(xiàn)。
[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，

本文編號(hào)：1656089