Light-Controlled Self-Assembly of Semiconductor Nanoparticles into Twisted Ribbons

Abstract

The collective properties of nanoparticles manifest in their ability to self-organize into complex microscale structures. Slow oxidation of tellurium ions in cadmium telluride (CdTe) nanoparticles results in the assembly of 1- to 4-micrometer-long flat ribbons made of several layers of individual cadmium sulfide (CdS)/CdTe nanocrystals. Twisting of the ribbons with an equal distribution of left and right helices was induced by illumination with visible light. The pitch lengths (250 to 1500 nanometers) varied with illumination dose, and the twisting was associated with the relief of mechanical shear stress in assembled ribbons caused by photooxidation of CdS. Unusual shapes of multiparticle assemblies, such as ellipsoidal clouds, dog-bone agglomerates, and ribbon bunches, were observed as intermediate stages. Computer simulations revealed that the balance between attraction and electrostatic repulsion determines the resulting geometry and dimensionality of the nanoparticle assemblies.

Spatially and temporally reconfigurable assembly of colloidal crystals

“…The effect of light on colloids is typically due to radiation pressure, especially for a system with a mismatch between particle and solvent refractive index 17 . Light-induced assemblies have also been produced at the nanoscale for the specific case of cadmium telluride 18 and gold 19 nanoparticles. However, light can also be used to control the rate of chemical reactions, and therefore induce localized ion flows due to a spatial concentration gradient of reactants 20 .…”

Controlling the crystalline three-dimensional order in bulk materials by single-wall carbon nanotubes

“…Such control eases the processability of materials, especially their integration into devices. The incentive is to diminish the number of grain boundaries, on one hand, and macroscopic defects, on the other hand, which act as charge traps and/or affect the device performance [8][9][10] . A viable strategy to overcome such drawbacks implies the use of liquid crystals.…”

Advanced AuNMs as nanomedicine’s central goals capable of active targeting in both imaging and therapy in biomolecules

“…The AuNMs with preciselycontrolled vivid color possess abundant optical information and can encode biological or chemical recognition units to develop robust analytical methods in food safety, clinic diagnosis and so on. In addition, we are far from controllable assembly of AuNMs into the desirable structures of the collective properties [135].…”