Super stretchy semiconducting polymers

Silicon has enabled science journalists to cover topics that were once written about only by science fiction authors: implantable sensors, wearable smart gadgets, and even electronic skin. But silicon is naturally more rigid than is desirable for devices that ought to bend and stretch like living tissue. Some scientists have thus turned to semiconducting polymers to create such devices, but these materials have struggled to achieve flexibility without compromising electrical performance. An international research team has now created thin polymer films that can stretch up to twice their initial length while still allowing electrical charge to flow at rates comparable to silicon (Science 2017, DOI: 10.1126/science.aah4496). Led by Stanford University’s Zhenan Bao and Jong Won Chung of Samsung Advanced Institute of Technology, the team showed that wearable circuits made with the films can withstand bending, twisting, and even light stabbing. This ductile durability comes from confinement. When mixed with an elastic styrene copolymer, some conjugated polymers separate and confine themselves, forming nanoscopic, fibrous aggregates. This nanoconfinement impedes the semiconducting polymer’s inclination to crystallize and facilitates the movement of electrical charges, resulting in an uncompromising stretchy semiconductor, the team reports.