Templated synthesis of ZnSe nanostructures using lyotropic liquid crystals

Abstract

We report a technique for controlled synthesis of zero-, one-, and two-dimensional compound semiconductor nanostructures by using cubic, hexagonal, and lamellar lyotropic liquid crystals as templates, respectively. The liquid crystals were formed by self-assembly in a ternary system consisting of a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) amphiphilic block copolymer as the surfactant, heptane as the non-polar dispersed phase, and formamide as the polar continuous phase. ZnSe quantum dots and nanowires with diameters smaller than 10 nm, as well as free-standing, disc-like quantum wells, were grown inside the spherical, cylindrical, and planar nanodomains, respectively, by reacting diethylzinc that was dissolved in the heptane domains with hydrogen selenide gas that was brought into contact with the liquid crystal in a sealed chamber at room temperature and atmospheric pressure. The shape and size of the resulting nanostructures can be manipulated by selecting the templating phase of the liquid crystal, the size of the dispersed nanodomains that is controlled by the composition of the template, and the concentration of diethylzinc in them.