Electrically controlled polarized photoluminescence of CdSe/ZnS nanorods embedded in a liquid crystal template

Abstract

A novel homogeneous composite material, consisting of luminescent CdSe/ZnS quantum nanorods, embedded in the nematic liquid crystal 5CB, has been prepared. Liquid crystal cells and free-standing stretched polymer films incorporating this composite material were characterized using polarized micro-photoluminescence and electro-optical measurements under an applied electric field. A liquid crystal induced, macroscopic orientation of the nanorods in a thin layer of the material has been demonstrated. A conventional liquid crystal cell, filled with this composite, exhibits 40% modulation of the nanorod's photoluminescence intensity when subjected to an external electric field. These results indicate that quantum nanorods may have practical applications in photonic devices.

Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

“…Nanoparticles employed in such dispersions are often based on inorganic or mineral materials [ 20 , 21 ] such as dielectric and ferroelectric particles like TiO 2 [ 22 ] and Sn 2 P 2 S 6 [ 23 ] or BaTiO 3 [ 24 , 25 ], gold nanoparticles [ 26 ] or carbon based nanotubes [ 27 , 28 ] and graphene oxide [ 29 ]. However, also other nanotubes, like ZnO [ 30 ] or semiconducting CdSe [ 31 ] have been employed to add additional functionality to the LC matrix. Not surprisingly, many of the shape-anisotropic dopants can also form LC phases by themselves, through dispersion in isotropic solvents.…”

“…Liquid crystalline self-assembly of nanorods has been reviewed recently by Thorkelsson et al [ 136 ]. Not only have semiconducting nanorods been investigated for the formation of lyotropic LCs, but also within LC templates [ 31 ].…”

Ordering of ferromagnetic nanoparticles in nematic liquid crystals

“…This has been demonstrated for example in a variety of systems combining nematic [8], smectic [9], lyotropic [10] or discotic [11] liquid crystals with carbon nanotubes. Also other rod-like particles with pronounced aspect ratios have been used, mostly ZnO nanorods [12,13], but also those prepared from gold [14], or CdSe [15]. The underlying idea in all of these systems is the enhancement of optical, elastic, electric or magnetic responses through shape-anisotropic particles, dispersed and oriented within a liquid crystal matrix.…”

Anisotropic absorption of CdSe/ZnS quantum rods embedded in polymer film

“…For all of the benefits nanostructured materials offer, their building blocks, colloidal nanocrystals, exhibit complex interaction between themselves, with matrix or substrate, that makes difficult to manipulate of nanocrystals and form the periodically ordered ensemble. There is a variety of approaches to nanocrystals ordering such as lithography techniques (Tamborra et al 2007), biomimetic (Dutta and Hofmann 2003), template- (Yin et al 2001) and matrix-assisted (Wu et al 2010, Mukhina et al 2012 approaches.…”

“…The nanocrystal-matrix interface and the morphology of the nanostructured material determine the degree of nanocrystals ordering in the matrix-assisted approach. Modification of the nanocrystal's surface with different types of solubilizers is required in most cases to achieve a good morphology of material (Mukhina et al 2012). However, chemical affinity of the material components allows us to use blending without the nanocrystal's surface modification.…”