The mechanism of the stability improvement of the B$upgamma$-CsSnI3 perovskite doped with fluorine
The mechanism of the stability improvement of the B$upgamma$-CsSnI3 perovskite doped with fluorine
复制标题
氟掺杂B$upgamma$-CsSnI3钙钛矿稳定性提高机制
DOI：
10.1088/2053-1591/ab5dd6
复制
发表时间：
2019
影响因子：
2.3
通讯作者：
Jian Wang
中科院分区：
文献类型：
--
作者：
Zhuo Zhao;Junsheng Wu;Fang Fang;Tong Li;Yanwen Zhou;Jian Wang
Determining the stability mechanism of perovskite materials is one of the key factors to promote the industrialization of perovskite solar cells. In this paper, we calculated and compared the lattice and electron structure, the differential charge density of intrinsic and fluorine (F) doped B-γ-CsSnI 3 phases by Density Functional Theory (DFT) method to explain the mechanism of stability. The results showed that as the volumes of the B-γ-CsSnI 3− x F x unit cell decrease, the distortions of the three-dimensional charge densities and electron localization functions become stronger, the formation energies reduce and the band gaps enlarge with the increases of F ratios. The transition from Sn 2+ to Sn 4+ is delayed because the strong electronegativity of F atom attracts the 3 electrons of Sn 5p. The phase transformations from the B-γ, Y phase to Cs 2 SnI 6− x F x phases are delayed as the F ratio increases, which is proved by differing colour change timings of CsSnI 3− x F x films with different doping levels of fluorine. The mechanism of the stability improvement of the B-γ-CsSnI 3− x F x perovskite is the strong influence of F hybridization, by partial substitution I with F, which results in a wider VBM and moving to low energy level, meanwhile the CBM moved to a higher energy level greatly, the electron densities and electron localizations strongly deform and electrons of Sn are tightly bound.
