Self-assembled "nano-flowers" created by Harvard researchers. Image Credits: Harvard University
In the quest for efficient and lower cost energy solutions, a structure that builds itself offers an intriguing solution. Harnessing self-assembly can allow complex nanostructures to be produced without intricate fabrication processes. These self-assembling structures can be used to create continuous sheets of materials for thermoelectric devices and solar cells.
The Nanoscale Challenge
Structures on the scale of 1-100 nanometers have been shown to have fascinating properties, distinct from the bulk-scale properties of the material they are made of. Accessing this range of structure-based properties has had an immense impact on the worlds of medicine, green energy, and advanced materials in countless applications.
However, these tiny structures are very difficult to create and manipulate. A nanometer is one millionth of a millimeter - at this scale, in between the molecular and the microscopic, conventional manufacturing tools are useless.
Benefits of Self-Assembling Nanostructures
Many nanostructures have been found to self-assemble in a "bottom-up" fashion. This property has the potential to greatly reduce the cost of nanostructure production - removing the need for expensive equipment and energy-intensive vaccum conditions.
For example, quantum dots (nanoparticles with particular electrical and optical properties dependent on their size and shape) have been found to self-assemble in some cases. Rod-shaped cadmium sulfide and silver sulfide quantum dots have been shown to form spontaneously when the correct chemical mixture is used, without any extra human manipulation to control their size and shape.
Quantum dots have been suggested as a next-generation material for use in electronic displays, solar cells, drug delivery systems, and even quantum computers - the ability to create them by simply mixing chemicals together could put them ahead of other competing nanomaterials in these fields.
Not all self-assembling structures have such clear practical uses, however - some have purely aesthetic value. A method developed by a team of researchers at Harvard allowed them to direct the formation of beautiful self-assembled "nano-flower" structures, by manipulating the concentrations of barium chloride, sodium silicate, and carbon dioxide as the nanocrystals formed.
Research into self-assembling nanostructures is continuing, and it seems certain that self-assembly will play an important role in the nano-manufacturing industry as adoption of nanotechnologies accelerates.