Tin(IV)-Tolerant Vapor-Phase Growth and Photophysical Properties of Aligned Cesium Tin Halide Perovskite (CsSnX₃; X = Br, I) Nanowires

All-inorganic Sn-based halide perovskites (CsSnX₃; X = Br, I) have near-infrared optical response and exhibit electronic properties comparable to those of their lead analogues. CsSnX₃ nanowires with controllable orientations and dimensions can further enable integrated optoelectronic devices and facilitate physical studies, but they are challenging to synthesize. Here, a facile and robust vapor-phase epitaxial method is developed to produce horizontally aligned high-quality CsSnX₃ nanowires and microwires with controllable dimensions on mica substrate for the first time. CsSnI₃ is in the α-cubic perovskite phase at the growth temperature, thus enabling the anisotropic lattice match with mica and epitaxial growth of the wires. The vapor growth is tolerant of Sn⁴⁺ in the SnX₂ precursor and produces high-quality materials regardless of the protective environment. Temperature- and power-dependent photoluminescence spectra reveal positive thermal expansion of the CsSnBr₃ wires upon temperature increase and that the nonradiative recombination processes in CsSnBr₃ are largely suppressed below 225 K.