Halogen-regulating synthesis of a novel semiconductor hybrid material [(CH3)3N(CH2)3Br]2ZnBr4 with high-temperature phase transition

Abstract

The continuous progress in the synthesis and characterization of materials in the vast family of hybrid organic–inorganic metal halide perovskites have been pushed by their exceptional properties mainly in optoelectronic applications. Here, we have used specific reagents to design and synthesize a low dimensional semiconductor material, [Br(CH₂)₃N(CH₃)₃]₂ZnBr₄ using slow evaporation method which is crystalized in a monoclinic system with a P2/c space group with cell parameters of a = 23.572 (3) Å, b = 9.4987 (10) Å, c = 15.8731 (16) Å, β = 91.440 (4)° and Z = 6 at room temperature. The crystal structure of [Br(CH₂)₃N(CH₃)₃]₂ZnBr₄ was determined to be zero-dimensional (0D). In this structure, the inorganic [ZnBr₄]²⁻ anions are completely isolated from each other. These anionic groups are separated by [Br(CH₂)₃N(CH₃)₃]⁺ cations. The UV-visible absorption spectrum of the polycrystalline sample estimates the band gap, which was found to be approximately 3.36 eV. Differential scanning calorimetric analysis exhibits one irreversible phase transition at 358 K. The XRD as function of the temperature confirms this transition by the change of the symmetry of this material. The temperature-dependent Raman scattering study analyzed in detail the full width at half-maximum (FWHM) of internal modes of the anions and cations which are connected by intermolecular C–H⋯Br hydrogen bonds and an intramolecular C–H⋯Br interaction. The change of energy activation confirms the phase transition. The electrical properties further validate the transition mechanism through the observed change in energy activation using the variation of the conductivity versus temperature.