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

• DOI: 10.1126/science.1177218
• Publication Date: 2010-02-12T03:44:46Z
• Authors: Sudhanshu Srivastava; Aaron Santos; Kevin Critchley; Ki-Sub Kim; Paul Podsiadlo; Kai Sun; Jaebeom Lee; Chuanlai Xu; G. Daniel Lilly; Sharon C. Glotzer; Nicholas A. Kotov
• Keywords: Microscale chemistry; Cadmium telluride photovoltaics; Cadmium sulfide; Agglomerate; Nanometre; Micrometer; Tellurium

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