Millimeter-scale ordered assembly of CdSe nanorods via fast solvent drying
C. Querner, M. D. Fischbein, P. Heiney, M. Drndic
CdSe nanorods (NRs) are important materials for a range of applications from solar cells to bio-labeling of DNA and protein molecules. NRs emit highly tunable wavelengths and linearly polarized light in the direction of their long axis. Developing ways to manipulate the position and orientation of nanorods is required for many studies and applications of these particles. Ordered self-assembly of such anisotropic nanocrystals is however more complicated than that of the spheres because of their reduced shape symmetry.
In this work, we showed that long-range (millimeter-scale) ordered assembly can be achieved by exploiting capillary flow of a fast drying droplet containing CdSe nanorods. These NR superstructures are formed as capillary flow causes many nanorod tracks, which act as building blocks, to the perimeter of the drying droplet. The resulting NR-tracks are composed of up to thousands of single NRs oriented side-to-side and these tracks align parallel to the droplet contours (so called “coffee-stain”contours).
C. Querner, M. D. Fischbein, P. Heiney, M. Drndic, Advanced Materials 20, in press, 2008.