Investigation on the structural, optical, photoluminescence and electric properties of a semiconductor material [Br(CH2)2N(CH3)3]2SnBr6

Abstract

A new low-dimensional hybrid tin(IV) halides, [Br(CH₂)₂N(CH₃)₃]₂SnBr₆, was synthesized via slow evaporation from acidic aqueous solution under ambient conditions. Single-crystal X-ray diffraction reveals that the compound crystallizes in the orthorhombic space group Pbca, featuring discrete [SnBr₆]²⁻ octahedra spatially isolated and electrostatically stabilized by [Br(CH₂)₂N(CH₃)₃]⁺ cations. The crystal packing is reinforced through a network of C–H⋯Br hydrogen bonds and halogen···halogen contacts, forming a 0D supramolecular framework. Infrared spectroscopy confirms the existence of characteristic vibrational modes from organic molecule. Furthermore, the thermal behavior studied by (TGA–DSC) indicates good thermal stability up to 430 K. Optical absorption studies yield a direct optical band gap of 3 eV and an indirect gap of 2.54 eV, consistent with semiconducting behavior. Under UV excitation, the compound exhibits blue photoluminescence centered at 434 nm, attributed to excitonic recombination confined within the [SnBr₆]²⁻ units. Impedance spectroscopy further reveals thermally activated conduction, following non-overlapping small polaron tunneling and correlated barrier hopping models. These findings suggest that [Br(CH₂)₂N(CH₃)₃]₂SnBr₆ is a structurally robust, lead-free semiconductor with blue emission, making it a promising candidate for environmentally benign optoelectronic devices such as LEDs and photonic components.