Self-assembly of monolayers of cadmium selenide nanocrystals with dual color emission

We report here a simple and low-temperature method to induce the patterning of monolayers of semiconductor nanocrystals with dual color emission. We have used the patterned self-assembled monolayers (SAMs) of alkanethiolates on gold as a template to assemble two specific size CdSe nanocrystals into regular two-dimensional arrays. The nanocrystal arrays on each region of SAMs are organized spontaneously on the basis of different interactions between specific size nanocrystals and alkanethiolates of SAMs. As characterized by scanning probe microscopy, scanning electron microscopy, and optical spectroscopy, our results show that small and specific size nanocrystals can be assembled into large monolayer arrays with micrometer-scale features. Our method provides a new way to assemble semiconductor nanocrystals and should be useful for the fabrication of optical and electronic devices composed of nanocrystals.