We deposit droplets of nanorods dispersed in solvents on substrate surfaces and let the solvent evaporate. We find that strong contact line pinning leads to dense nanorod deposition inside coffee stain fringes, where we observe large-scale lateral ordering of the nanorods with the long axis of the rods oriented parallel to the contact line. We observe birefringence of these coffee stain fringes by polarized microscopy and we find the direction of the extraordinary refractive index parallel to the long axis of the nanorods.
@article{arxiv.0812.5041,
title = {Self assembly of highly fluorescent semiconductor nanorods into large scale smectic liquid crystal structures by coffee stain evaporation dynamics},
author = {Concetta Nobile and Luigi Carbone and Angela Fiore and Roberto Cingolani and Liberato Manna and Roman Krahne},
journal= {arXiv preprint arXiv:0812.5041},
year = {2015}
}