Introduction
© 2006 ACS
The self-assembly of molecules that have good charge-mobility characteristics is a promising approach for the construction of nanoscale devices. However, a major challenge is to precisely control the dimensions and stability of the resulting structures. Furthermore, research has largely focused on p-type (hole conducting) rather than n-type (electron conducting) molecules, although electronic applications require both.
Now, Alex Jen and co-workers1 of the University of Washington in the USA and Sichuan University in China have assembled one-dimensional nanowires from n-type molecules. These large disc-like molecules stack face-to-face to form columns because of interactions between their delocalized electron systems. The length of the nanowires can be easily controlled; as the concentration of the molecules increases, so does the length of the nanostructures. They can be up to 10 
m long, but always just one molecule (20 nm) wide. In order to make more robust structures, the outer rim of the molecules can be decorated with groups that become crosslinked with one another when exposed to ultraviolet light.
Jen and colleagues go on to pattern surfaces with these self-assembled nanowires using a simple microcontact printing technique, which is the first step along the road to making functional devices from these nanostructures.
