Fabrication of one-dimensional nanostructures standing vertically on a substrate through layer-by-layer deposition.

Layer-by-layer deposition has been widely used to prepare heterogeneous nanocomposites with controllable properties, where the controllability of nanocomposite properties can be further enhanced by combining the self-assembly of hard materials, such as nanocrystals, and soft materials, such as polymer matrices. However, the self-assembled structure of nanocrystals in a polymer matrix is limited by thermodynamics. Herein, we introduced the strong interaction between nanocrystals and a substrate to generate a thermodynamically unfavorable one-dimensional nanostructure standing vertically on the substrate. Two different shapes-"wire-like" and "steeple-like" or "antenna-like"-of one-dimensional nanostructures standing vertically on the substrate can be obtained using cube-like nanocrystals as building blocks and carefully controlling their size in each deposited layer. This low-cost and massively parallel scale synthesis method to generate one-dimensional nanostructures standing vertically on a substrate can be used to replace the expensive and time-consuming "lithography" synthesis method. This synthesis method also provides a simple way to design and fabricate one-dimensional nanostructures with desired properties standing vertically on a substrate by controlling nanocrystal properties in each deposited layer.