(538d) Photothermal Assembly and Modification of Nanomaterial Heterostructures

While progress in colloidal synthesis has enabled the production of materials with highly tunable electronic and optical properties, engineering devices from colloidal materials has remained difficult. A unifying challenge in the production of devices from these colloidal nanomaterials is the creation of junctions, most frequently heterostructures. Light-matter interactions offer the ability to target subpopulations of nanomaterials from a dispersion and photothermally heat or pattern individual particles. For example, optical traps can be used to manipulate individual nanoparticles in three dimensions, assemble complex structures, and photothermally superheat solutions. However, there are relatively limited reports on optical trapping in non-aqueous media.

Here, for the first time, we demonstrate the fabrication of nanocrystal-nanowire heterostructures through the alignment, manipulation, and modification of nanowires in non-aqueous media with an optical trap. Using a colloidal growth process that yields metal nanocrystal-tipped nanowires, we synthesized anisotropic nanowires. During trapping, the near-infrared laser generates an anisotropic radiation pressure which enables alignment of the nanowires, and the high absorption coefficient of the metal seed yields high local temperatures. Leveraging these effects, we demonstrate the assembly of nanowire-nanocrystal heterostructures. Finally, we conclude the talk with some exciting results on the large-scale photothermal modification of nanomaterials.