Zhang Qiang, Xin Tianyuan, Lu Xiaoke, Wang Yuexia
Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433, China.
Materials (Basel). 2018 Mar 16;11(3):431. doi: 10.3390/ma11030431.
We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te), i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT) method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently.
我们利用了一种结构类似于磷烯的新型二维（2D）碳硒化物（CSe），并对其电学和光电子学性质进行了探究。使用密度泛函微扰理论（DFPT）方法计算声子谱表明，二维CSe具有动态稳定性，这使得通过X掺杂（X = O、S、Te），即X取代Se原子，来调控并赋予CSe优异性能成为可能。然后，我们使用密度泛函理论（DFT）方法对原始的和X掺杂的单层CSe的结构、电子和光学性质进行了系统研究。结果发现，C-X键的特征与掺杂原子的电负性和半径密切相关，这导致掺杂不同的第VI族元素时会产生不同的电子和光学性质。除了O掺杂外，所有体系都具有直接带隙。在单层CSe中用O取代Se原子会导致从直接的Γ-Γ带隙转变为间接的Γ-Y带隙。此外，带隙值会随着掺杂浓度和掺杂原子半径的增加而减小。掺杂后吸收光谱会向可见辐射范围发生红移，并且随着掺杂原子半径和浓度的增加，红移现象变得更加明显。这些结果对于根据掺杂原子的半径或电负性来筛选掺杂原子以有效调整光谱可能是有用的。
