Thermal, ferroelastic, and structural properties near phase transitions of organic-inorganic perovskite type [NH3(CH2)3NH3]CdBr4 crystals

Hybrid perovskites have potential applications in several electrochemical devices such as supercapacitors, batteries, and fuel cells. Therefore, we studied the thermal behavior and structural dynamics of organic-inorganic hybrid perovskite [(NH3)(CH2)(3)(NH3)]CdBr4 crystals near phase transition temperatures, T-C2 (=328 K) and T-C1 (=363 K), which are correlated to the structural dynamics of cations and anions. The structural geometry and molecular dynamics with emphasis on the role of the [(NH3)(CH2)(3)(NH3)] cation and CdBr6 anion were discussed in terms of MAS H-1 NMR, MAS C-13 NMR, N-14 NMR, and Cd-113 NMR as a function of the temperature. The environments surrounding H-1, C-13, N-14, and Cd-113 are investigated near T-C1 and T-C2 using these results. Spin-lattice relaxation times T-1 rho were discussed in terms of the change in temperature. The discontinuous changes of H-1 T-1 rho and C-13 T-1 rho near T-C1 are consistent with the change of the lattice constant. Shorter T-1 rho values at high temperature indicate that H-1 and C-13 in the organic chains are more flexible at these temperatures. Based on these results, the physicochemical properties of the cation and anion during the III-II-I phase transitions were discussed. This study was conducted to improve the relatively weak thermal stability compared to the high efficiency for a variety of applications.