Temperature-Dependent Evolution of Raman Spectra of Methylammonium Lead Halide Perovskites, CH<sub>3</sub>NH<sub>3</sub>PbX<sub>3</sub> (X = I, Br)
Kousuke Nakada,
Yuki Matsumoto,
Yukihiro Shimoi,
Koji Yamada,
Yukio Furukawa
Affiliations
Kousuke Nakada
Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
Yuki Matsumoto
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
Yukihiro Shimoi
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
Koji Yamada
College of Industrial Technology, Nihon University, Izumi-cho 1-2-1, Narashino, Chiba 27-8575, Japan
Yukio Furukawa
Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
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−1 for MAPbBr3 and at ~240 cm−1 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.
