硫掺杂卤氧化铋的电子结构和光学性能

Electronic structure and optical properties of sulfur-doped halogenated bismuth oxide

关键词:  第一性原理  卤氧化铋  硫掺杂  电子结构  光学性能

Key words:  first principles  bismuth halooxide  sulfur doping  electronic structure  optical performance

摘要:

卤氧化铋因其独特的层状和高度各向异性的晶体结构而受到研究者的广泛关注,但较低的分离和传输效率导致的光生载流子严重复合,同时较宽的禁带宽度,使其光吸收范围仅局限于部分可见光,甚至仅在紫外光区域,极大地影响了其光催化性能。为了解决上述问题,本文致力于使用密度泛函理论的第一性原理方法,通过Mulliken布居、能带结构、态密度、介电函数以及吸收光谱等,从理论上探讨硫掺杂卤氧化铋体系对其电子结构和光学性能的影响。研究表明,硫掺杂卤氧化铋后,体系均发生轻微晶格畸变,但仍保持独特的层状结构；S的3p轨道形成杂质能级,使带隙明显减小,增强了光吸收性能,有利于光催化反应的进行。体系的介电虚部均向低能级移动,静介电常数均增大,极化能力增强,有利于载流子的迁移与分离。

Abstract:

Bismuth halide has attracted more and more attention due to its unique layered and highly anisotropic crystal structure.However,due to the low separation and transmission efficiency,the photogenerated carriers are seriously recombined, and the wide bandgap limits their light absorption range to only a portion of the visible light or even only in the ultraviolet region, which greatly affects its photocatalytic performance. In order to solve the above problems, using density functional theory as a first-principles method, this paper focuses on exploring the influence of sulfur-doped bismuth halide system on its electronic structure and optical properties through Mulliken distribution, band structure, density of states, dielectric function and absorption spectra. The results show that after sulfur-doped bismuth halide bismuth oxide, the system undergoes slight lattice distortion, but still maintains a unique layered structure. The impurity energy level formed by the S 3p orbital significantly reduces the band gap and enhances the light absorption performance, which is conducive to the photocatalytic reaction. The dielectric imaginary part of the system moves to lower energy level, the electrostatic dielectric constant increases, and the polarization ability increases, which is conducive to the migration and separation of carriers. In this paper, the effect of S doping on the bismuth halide system is studied theoretically, which has strong guiding significance for the modification of the bismuth halide system.