Crystal growth, phase transition, and nuclear magnetic resonance of organic–inorganic hybrid perovskite NH2(CH3)2CdCl3

Abstract

Understanding the physicochemical properties of organic–inorganic hybrid materials is essential to promote their applications. In this study, a single crystal of NH₂(CH₃)₂CdCl₃ was grown, and it exhibited a monoclinic structure. Its phase transition temperatures were 460 and 470 K, and it showed sufficient thermal stability. The changes in the NMR chemical shifts of each atom in the crystal with increasing temperature were determined; the chemical shift of ¹H of NH₂ in the NH₂(CH₃)₂ cation changed with temperature, which was correlated to the changes in the chemical shift of ¹⁴N in NH₂. The change in ¹¹³Cd chemical shifts indicate the change of six Cl atoms around Cd in CdCl₆. Therefore, the change in the coordination geometry of CdCl₆ is attributed to the change in the N–H⋯Cl hydrogen bond between the NH₂(CH₃)₂ cation and CdCl₆ anion. In addition, the ¹³C activation energies E_a obtained from the spin-lattice relaxation time T_1ρ values are smaller than those of the ¹H E_a values, suggesting that is free compared to ¹H in the cation. We believe that this study furthers our fundamental understanding of organic–inorganic hybrid materials to promote their practical solar cell applications.