Controlled Ligand-Free\nGrowth of Free-Standing CsPbBr<sub>3</sub> Perovskite Nanowires

Metal halide perovskite nanowires are widely studied\ndue to their\nunique electronic and optical characteristics, making them promising\nfor light emitting and detection applications. We developed a ligand-free\nmethod to grow vertically aligned free-standing CsPbBr<sub>3</sub> nanowires from anodized aluminum oxide nanopore substrates. Here,\nwe investigate the growth process using <i>in situ</i> microscopy\nwith ultraviolet and visible light excitation, revealing a highly\ndynamic process with pronounced fluorescence at locations where high-density\nfree-standing nanowires could be found. The yield of the growth is\nstrongly improved by using a growth reactor with controlled N<sub>2</sub> flow, increasing from 17 to 60%. We systematically investigated\nthe growth dependence on the temperature and N<sub>2</sub> flow rate\nand identified optimal parameters at 70 °C and 0.8 L/min, respectively.\nThe improved control over the growth of free-standing nanowires expands\nopportunities for their integration into optoelectronic devices.