“…25 Although the effect of adding different concentrations of PEI on the morphology and the properties of ZnO NWs has been amply documented in the literature, the comparison of the influence of the molecular weight keeping all other parameters the same has not yet been explored. A diverse set of PEI molecular weights has been studied, with values ranging from low, i.e., 800, 13,21 4000, 18 4500, 17 to as high as 70 000, 24 or 750 000, 26 whereas, in several other works, the molecular weight is not specified. 12,14,16,20,22,23,25 The brief survey presented above demonstrates that, despite the vast number of attempts to optimize the growth parameter of the CBD, further exploration is still indispensable for improving the physical properties of the ZnO nanowire arrays, including the concurrent control of their aspect ratio, the NW height growth rate, and the density of defects.…”