Synthesis and characterization of a hybrid perovskite with an imidazole spacer for optoelectronic applications

Abstract

Perovskites are an emerging class of materials that have attracted significant attention from the scientific community due to their semiconductor properties. Three-dimensional hybrid perovskites demonstrate good performance in optoelectronic devices, such as solar cells and light-emitting diodes (LEDs). The predominant use of lead ions (Pb²⁺) in the composition of perovskites, although effective in terms of efficiency, raises concerns related to toxicity and limited stability under ambient conditions. In this context, tin (Sn) has emerged as a promising substitute for lead, reducing toxicity without compromising performance. In addition to replacing Pb with Sn, the incorporation of novel organic cations into the structure of hybrid perovskites has been considered a promising strategy to improve their chemical and environmental stability. This modification leads to the formation of hybrid organic-inorganic metal halides, which enhance the structural integrity and influence the electronic and optical properties of the material. In this work, the hybrid perovskite (C₁₁H₁₁N₂O)₂SnBr₆ was synthesized using a slow evaporation method in an acidic medium. The structure incorporates the organic cation 2-(1H-imidazol-1-yl)-1-phenylethanone, while Sn⁴⁺ coordinates six bromide atoms, forming the [SnBr₆]²⁻ octahedron. The resulting crystalline organization is classified as a zero-dimensional (0D) perovskite, composed of isolated octahedral units. The compound exhibits broad-band emission across a large portion of the visible spectrum. This feature is associated with the radiative recombination of self-trapped excitons (STEs), a phenomenon commonly observed in hybrid halide perovskites. In addition to its structural stability, a key factor for practical applications, the perovskite displays a direct optical bandgap of 2.99 eV, making it a potential candidate for optoelectronic devices. Thus, this research contributes to the development of alternative materials that not only offer competitive performance compared to conventional lead-based perovskites but also address challenges related to sustainability and toxicity, broadening the scope for safe and efficient technological applications.