论文标题
理论研究有机阳离子在碘化甲基二叶钙钛矿中的作用
Theoretical investigation of the role of the organic cation in methylammonium lead iodide perovskite
论文作者
论文摘要
混合卤化物Perovskite ch $ _3 $ nh $ _3 $ pbi $ _3 $易于制造和便宜。尽管如此，它作为太阳能电池的效率与当今有效的太阳能电池相当。由于这些原因，今天它引起了很多关注。但是，CH $ _3 $ _3 $ nh $ _3^+$（mA）分子在钙钛矿结构中对电子和结构属性的影响仍然是辩论的问题。先前的研究通常集中在MA分子的旋转上。在这项研究中，从不同的角度研究了MA分子沿C-N轴运动的影响。通过这种方法，以更具控制的方式检查了MA分子的作用。在这项研究中，在案例计算中使用了范德华（VDW）相互作用的密度功能理论（DFT）。根据获得的数据，在MA分子和无机框架之间形成了H-I离子键。在结构内，尽管MA的位置发生了变化，但H-I键长倾向于保留。在这种机制中，i离子通过远离PB-i-PB对准的位置来发挥重要作用。 I离子的位置决定了带隙跃迁的性质。另一个效果是对带隙的值。根据I离子的位置，带隙可能会缩小约0.26 eV。通过MA分子的效果，I离子与PB-I-PB比对的分离破坏了反对称性。根据从这项研究中获得的数据，条带隙中的这种机制是由于晶体结构中反对称性的破坏所致。
The hybrid halide perovskite CH$_3$NH$_3$PbI$_3$ is easy to manufacture and inexpensive. Despite these, its efficiency as a solar cell is comparable to today's efficient solar cells. For these reasons, it is attracting a lot of attention today. However, the effects of the CH$_3$NH$_3^+$ (MA) molecule in the perovskite structure on the electronic and structural properties are still a matter of debate. Previous studies have generally focused on the rotation of the MA molecule. In this study, from a different perspective, the effects of the movement of the MA molecule along the C-N axis are investigated. With this method, the effects of the MA molecule were examined in a more controlled way. In this study, density functional theory (DFT) that accounts for van der Waals (vdW) interactions was used in the calculations for the cases. According to the data obtained, H-I ionic bonds are formed between the MA molecule and the inorganic framework. Within the structure, the H-I bond length tends to be preserved, although the position of the MA changes. In this mechanism, the I ion plays an important role by moving away from its place in the Pb-I-Pb alignment. The position of the I ion determines the nature of the band gap transition. Another effect is on the value of the band gap. Depending on the position of the I ion, the band gap may narrow by about 0.26 eV. The separation of the I ion from the Pb-I-Pb alignment by the effect of the MA molecule breaks the inverse symmetry. According to the data obtained from this study, this mechanism in the band gap is due to the breaking of the inverse symmetry in the crystal structure.
