Crystal structure, semiconducting and photoluminescence (PL) properties of hybrid tin perovskite-like materials: [Cl–(CH2)2–NH3]2SnCl6 and [Cl–(CH2)2–NH3]2SnBr5.65Cl0.35

Abstract

Hybrid halide perovskite-like materials have recently attracted great interest due to their potential applications in optoelectronic devices, energy storage and the semiconductor industry. In this work, two tin(IV) based organic–inorganic hybrid compounds [Cl–(CH₂)₂–NH₃]₂SnCl₆(1) and [Cl–(CH₂)₂–NH₃]₂SnBr_5.65Cl_0.35(2) were prepared by the reaction of 2-chloroethylamine hydrochloride with SnX₂ (X = Cl, Br) in the corresponding concentrated halogen acids. Single-crystal X-ray diffraction analysis reveals that compounds (1) and (2) are isotypic and crystallize in the monoclinic system with space group P2₁/m. The asymmetric unit of the crystal structure in each compound is composed of an independent [SnX₆]²⁻ anion charge balanced by [Cl–(CH₂)₂–NH₃]⁺ cations, where X is a halogen. Differential scanning calorimetry (DSC) and electric measurements show that no phase transition occurs in the hybrid compounds over the temperature range of 298–453 K. Interestingly, both materials exhibit a semiconducting property with optical bandgaps of 4.7 eV for (1) and 2.94 eV for (2). Photoluminescence (PL) measurements evidenced the presence of green emissive traps activated by excitation below the optical gap for the [Cl–(CH₂)₂–NH₃]₂SnCl₆(1) compound, resulting in an emissive color change of the crystals, from blue to green. These findings of Sn(IV)-based metal halides with prominent semiconducting behaviors and photoluminescence properties contribute to the exploration of new types of hybrid perovskite-like with adjustable properties.