A solar panel that could ball-up to the size of a grapefruit and expand to the size of a room, created from super-compliant fracture-proof electronics — that's Darren Lipomi's dream.
The professor in the department of nanoengineering at University of California at San Diego (UCSD) envisions a world filled with self-repairing sensor “skins,” each made from a super-thin layer of organic stretchable material similar to a thin piece of plastic, pliable as foil, allowing a semiconductor to conform to the object and stretch with movement.
How would this next phase of bendable materials influence changes in the supply chain? For starters, it could turn flexible electronics into another layer of skin, giving new meaning to the phrase “mobile technology.” OEMs will need to alter manufacturing processes to accommodate the transition.
Lipomi (along with UCSD colleagues Suchol Savagatrup, Adam D. Printz, Timothy F. O'Connor, and Alizksandr V. Zaretski) is exploring the use of different types of electronics with molecular structures that permit conductive materials to function continuously when deformed or contorted in any direction during long periods of time.
By determining the structural details of organic semiconductors at the molecular level, the scientists believe it would enable super-thin film-like materials — of 100 nanometers — to stretch without the loss of electronic functions. A thickness of about one hundred billionth of a meter is usually more than enough material to emit light in displays, he says.
Think of a thin, stretchable second skin on any object such as a baseball or piece of clothing. His passion lies with solar panels, which he describes as a very large fracture-proof solar module for utility-scale projects to generate electricity. He also sees use for commercial displays in wearable devices like clothing and watches from Apple, Google, LG, Samsung, Microsoft, and others.
The research identifies general types of stretchable electronic materials and provides examples of applications. The research also suggests the main challenge is to gain a better understanding of the ways in which molecular structure simultaneously influences electronic and mechanical properties in order to make it bendable.
There are challenges. Janine Love wrote about several in December 2013. While there's a big knowledge gap in going from something in the laboratory to a commercial product, Lipomi expects to see the use of this stretchable organic material within 10 to 20 years. That will depend on how well the community works together to develop processes and the technology.
Larger problems come out of the woodwork when expanding from small applications to larger projects. Success will mean finding a way to integrate organic materials, so electronics perform consistently in flexible materials.
The ability to obtain good electronic properties from highly amorphous films seems to represent one way, while another points to a method that prepares stretchable nanowire “fabrics” from solution processing or electrospinning. The research calls the later the “middle ground between composite and molecular approaches to elastic semiconductors.”
Finding the solution will require collaboration between device engineers, materials scientists, synthetic chemists, and theorists specializing in both electronic structure calculations and the mechanical behavior of soft materials — all in order to meet the challenges represented by high-performance molecular semiconductors with predictable mechanical properties, following the research.