Effect of Chlorine Substitution on Lattice Distortion and Ferroelectricity of CH3NH3PbI3

详细信息    查看全文

• 作者：Wen-Li Yan ; Guang-Hong Lu ; Feng Liu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：August 18, 2016
• 年：2016
• 卷：120
• 期：32
• 页码：17972-17977
• 全文大小：387K
• 年卷期：0
• ISSN：1932-7455

文摘

As a prototype of organic–inorganic hybrid perovskites, CH₃NH₃PbI₃ is attracting extensive attention because of its applications in high-power-conversion-efficiency solar cells. However, the mixed-halide perovskite CH₃NH₃PbI_3–xCl_x exhibited superior carrier diffusion properties in recent experiments. Using first-principles calculations and the Berry phase method, we calculated the crystal structures and ferroelectric properties of pure and Cl-doped CH₃NH₃PbI₃. The off-center displacement of Pb within the PbI₆ octahedron was found to introduce major intrinsic polarization, rather than the off-center displacement of CH₃NH₃⁺ within the inorganic lattice or charge polarization within the organic cation, as expected. With chlorine substitution for iodine, the larger electronegativity difference between the halogen and Pb increases the lattice distortion and, hence, the electric polarization increases by as much as ∼50%, which provides a possible mechanism to further assist carrier separation and diffusion in solar cell devices.