Air/water Interfacial Assembled Semiconductor Films for Stretchable Organic Electrochemical Transistors

With the vigorous development of organic materials, organic electrochemical transistors (OECTs) have attracted considerable attention in the field of organic electronics owing to their high transconductances, low operating voltages (< 1 V), and excellent biocompatibility. However, the absence of stretchable semiconductor films for OECTs, where mechanical deformation occurs, induces a consequent degradation in electrical performance. Here, we report the fabrication of high-performance stretchable semiconductor films by incorporating a blend organic semiconductor layer, which is composed of poly(3-hexylthiophene) (P3HT) and polyethylene oxide (PEO), and the development of fully flexible OECTs. To address this issue, the stretchable semiconductor films are assembled into a freestanding film by the air/water interface assembly technique. Furthermore, adjusting the number of stacked layers of the P3HT/PEO film allows controllable OECT output without compromising the on/off current ratio. Benefiting from the elastic blend semiconductor films, the corresponding stretchable OECTs exhibit robust mechanical endurance and maintain their reliable electrical characteristics when subjected to a 40% strain. Besides, artificial synapses based on these OECTs showed good stability upon 30% strain. This work paves the way for a universal design strategy to achieve high-performance stretchable OECT devices and could be extended to other flexible/stretchable electronics.