New Flexible N-Type Semiconductors Could Usher in a New Era of Truly Flexible Integrated Circuits
Joining existing flexible p-type devices, these sandwich-style n-type semiconductors can drive complex devices — like an image sensor.
Researchers from Pennsylvania State University, the University of Houston, Pusan National University, the Ulsan National Institute of Science and Technology (UNIST), Nanjing's Southeast University, Northwestern University, and Flexterra have developed a new flexible n-type semiconductor, which they say could lead to soft and stretchy electronics for everything from human-machine interfaces to robotic sensing systems.
"Such technology requires stretchy elastic semiconductors, the core material needed to enable integrated circuits that are critical to the technology enabling our computers, phones and so much more, but these semiconductors are mainly p-type," explains Cunjiang Yu, associate professor and principal investigator on the project. "However, complementary integrated electronics, optoelectronics, p-n junction devices and many others, also require an n-type semiconductor."
While flexible p-type semiconductors are a largely solved problem, n-type semiconductors have proven more troublesome — tending towards a brittleness which limits just how much strain a flexible device built using them can take. Without n-type semiconductors, the complexity of truly flexible electronics is sorely limited — which is where the team's breakthrough comes in.
By creating an electronic "sandwich" with the n-type semiconductors placed between two elastomer layers, the research team was able to create flexible versions of previously-rigid devices — including an image sensor — capable of withstanding more strain than ever before. "We found that the stack architecture improves mechanical stretchability and suppresses the formation and propagation of microcracks in the intrinsically brittle n-type semiconductor," Yu explains.
"The elastic transistors retained high device performance even when stretched 50 percent in either direction," Yu says of the prototypes' performance. “The devices also exhibited long-term stable operation for over 100 days in an ambient environment. Now we have a stretchy n-type semiconductor, and we will soon have stretchy rubbery integrated circuits. Isn't it exciting?"
The team's work has been published in the journal Nature Electronics under closed-access terms.
