Structural phase transition, vibrational analysis, ionic conductivity and conduction mechanism studies in an organic-inorganic hybrid crystal: [N(CH3)3H]2CdCl4

Abstract

Hybrid organic-inorganic metal halides (HOMHs) present good application prospects in optoelectronics and photovoltaic as a result of their richness in physical properties and diverse structural assemblies. Herein, the organic-inorganic hybrid compound, [N(CH3)3H]2CdCl4 (1) is successfully synthesized by slow evaporation at room temperature. X-ray powder diffraction shows that 1 crystallizes in the orthorhombic system with the space group Pna21. The chemical composition of 1 is discussed by a STEM−EDS. Two-phase transitions at T1=253/263 ​K and T2=290/300 ​K are confirmed by the differential scanning calorimetry (DSC) curve. The measurements of the electrical properties are performed in the 10−1−107 ​Hz frequency range and 220−335 ​K temperature interval. The study on the charge transfer mechanism of 1 is done with the help of Elliott’s theory. The conduction mechanism in 1 is interpreted by different approaches: the correlated barrier hopping (CBH) model in phase I, the non-overlapping small polaron tunneling (NSPT) model in phase II, and the overlapping large polaron tunneling (OLPT) model in phase III.