PORTLAND, Ore. A new processing technique developed by Cornell University researchers promises to usher in lithographic-like self-assembly into single and multidimensional nanoscale structures. The technique enabled 10-nm precision lithography.
One-, two- and three-dimensional nanoscale structures self-assembled by combining a block copolymer with a "cascade molecule" called a dendrimer in which atoms are arrayed along a carbon backbone, the researchers said.
"We demonstrated 10-nanometer feature sizes, but we envision our invention working with traditional lithography to encode information into a material that enables it to self-assemble into domains with angstrom-scale precision," said Ulrich Wiesner, professor of materials science and engineering at Cornell University.
Besides subnanoscale precision lithography, the researchers said their invention could lead to ultraprecise nanoscale features that improve the efficiency of batteries, solar cells and fuel cells.
In living organisms, molecules begin with individual one-dimensional properties that spontaneously self-assembly into two- and then three-dimensional structures. Using carefully crafted "seed" molecules, the final two-
and three-dimensional characteristics of the material can be be made to self-assemble with nanoscale precision.
The combination of a block copolymer with a dendrimer molecule resulted in a new class of synthetic macromolecules dubbed "extended amphiphilic dendron." Amphiphilic dendrons exhibit behavior that researchers have long sought to harnass.
The Cornell investigators demonstrated a range of novel nanoscale structures with 10-nm precision which were preordained to self-assemble using amphiphilic dendrons. Nanoscale-precise, continuous 3D cubes, double sandwiches and cylinders were demonstrated.
The researchers also showed how cylinders
phase-transition into 2D structures and then into 3D structures. What's more, when doped with
lithium salts, an ion-transport mechanism was enhanced to propel charge carriers along nanometer-sized self-assembled channels.
"We think that batteries, fuel cells and solar cells will all be able to refine their nanoscale features to enhance the conductivity of their underlying materials, thereby greatly improving their efficiency," said Wiesner.
Next, the researchers will investigate using induced
self-assembly to create a "supra-molecular switch" that could dramatically change its conductivity in response to slight changes in temperature, thereby enabling a super-sensitive temperature sensor.