Light-controlled self-assembly of semiconductor nanoparticles into twisted ribbons.
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.
Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
Sudhanshu
S
Srivastava
Aaron
A
Santos
Kevin
K
Critchley
Ki-Sub
KS
Kim
Paul
P
Podsiadlo
Kai
K
Sun
Jaebeom
J
Lee
Chuanlai
C
Xu
G Daniel
GD
Lilly
Sharon C
SC
Glotzer
Nicholas A
NA
Kotov
D019187:Cadmium Compounds / Q000737:chemistry; D003198:Computer Simulation; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry / Q000648:ultrastructure*; D008854:Microscopy, Electron; D010084:Oxidation-Reduction; D045663:Quantum Dots; D013052:Spectrometry, X-Ray Emission; D013440:Sulfides / Q000737:chemistry; D013691:Tellurium / Q000737:chemistry
D019187:Cadmium Compounds; D013440:Sulfides; C034939:cadmium sulfide; D013691:Tellurium; C028337:cadmium telluride