Chemically driven dimensionality modulation of hybrid tin(ii) halide perovskite microcrystals

Abstract

The lattice arrangement of lead-free perovskites can be altered by synthesis parameters such as concentration, temperature, choice of solvents, and the length of monovalent cations. This effect, often described as dimensionality modulation, can be exploited to develop new materials with better optical properties than their three-dimensional counterpart. This work explores the versatility of the hot-injection synthesis for obtaining 2-thiopheneethylammonium (TEA⁺) based tin halide perovskite microcrystals. The dimensionality of TEA-based tin bromide perovskite microcrystals can be modulated through changes in the TEA concentration, giving rise to the formation of highly luminescent 0D-TEA₄SnBr₆ and low-emissive 2D-TEA₂SnBr₄ microplates. In contrast, 0D-[TEASnCl₃][TEACl] and 2D-TEA₂SnI₄ are thermodynamically preferred as main products when using the chloride and iodide analogues, respectively, limiting the dimensional versatility. It is noteworthy that 0D-TEA₄SnBr₆ shows the highest PLQY from the low dimensional TEA tin halide family (PLQY = 75% in thin-film) owing to a more confined configuration based on isolated [SnBr₆]⁴⁻ octahedra moieties separated by TEA⁺ cations, being attractive for optoelectronic applications.