Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan.
Research Center for Computational Design of Advanced Functional Materials (CD-FMat), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
Molecules. 2019 Feb 11;24(3):626. doi: 10.3390/molecules24030626.
We present a Raman study on the phase transitions of organic/inorganic hybrid perovskite materials, CH₃NH₃PbX₃ (X = I, Br), which are used as solar cells with high power conversion efficiency. The temperature dependence of the Raman bands of CH₃NH₃PbX₃ (X = I, Br) was measured in the temperature ranges of 290 to 100 K for CH₃NH₃PbBr₃ and 340 to 110 K for CH₃NH₃PbI₃. Broad ν₁ bands at ~326 cm for MAPbBr₃ and at ~240 cm for MAPbI₃ were assigned to the MA⁻PbX₃ cage vibrations. These bands exhibited anomalous temperature dependence, which was attributable to motional narrowing originating from fast changes between the orientational states of CH₃NH₃⁺ in the cage. Phase transitions were characterized by changes in the bandwidths and peak positions of the MA⁻cage vibration and some bands associated with the NH₃⁺ group.
我们对有机/无机杂化钙钛矿材料 CH₃NH₃PbX₃（X = I，Br）的相变进行了拉曼研究，这些材料被用作具有高效率的太阳能电池。我们测量了 CH₃NH₃PbX₃（X = I，Br）在 290 到 100 K 温度范围内的 CH₃NH₃PbBr₃和 340 到 110 K 温度范围内的 CH₃NH₃PbI₃的拉曼谱带的温度依赖性。~326 cm 处的宽 ν₁ 带对于 MAPbBr₃ 和 ~240 cm 处的 MAPbI₃ 被分配到 MA⁻PbX₃ 笼振动。这些带表现出异常的温度依赖性，这归因于笼中 CH₃NH₃⁺的取向状态之间的快速变化引起的运动变窄。相变的特征在于 MA⁻笼振动和一些与 NH₃⁺基团相关的带的带宽和峰位置的变化。
