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.