Highly Stable Nonhydroxyl Antisolvent Polymer Dielectric:A New Strategy towards High-Performance Low-Temperature Solution-Processed Ultraflexible Organic Transistors for Skin-Inspired Electronics

Scarcity of the antisolvent polymer dielectrics and their poor stability have significantly prevented solution-processed ultraflexible organic transistors from low-temperature,large-scale production for applications in low-cost skin-inspired electronics.Here,we present a novel low-temperature solution-processed PEI-EP polymer dielectric with dramatically enhanced thermal stability,humidity stability,and frequency stability compared with the conventional PVA/c-PVA and c-PVP dielectrics,by incorporating polyethyleneimine PEI as crosslinking sites in nonhydroxyl epoxy EP.The PEI-EP dielectric requires a very low process temperature as low as 70℃ and simultaneously possesses the high initial decomposition temperature(340℃)and glass transition temperature(230℃),humidity-resistant dielectric properties,and frequency-independent capacitance.Integrated into the solution-processed C8-BTBT thin-film transistors,the PEI-EP dielectric enables the device stable operation in air within 2 months and in high-humidity environment from 20 to 100%without significant performance degradation.The PEI-EP dielectric transistor array also presents weak hysteresis transfer characteristics,excellent electrical performance with 100%operation rate,high mobility up to 7.98 cm^(2)V^(-1)s^(-1)(1 Hz)and average mobility as high as 5.3 cm^(2)V^(-1)s^(-1)(1 Hz),excellent flexibility with the normal operation at the bending radius down to 0.003 mm,and foldable and crumpling-resistant capability.These results reveal the great potential of PEI-EP polymer as dielectric of low-temperature solution-processed ultraflexible organic transistors and open a new strategy for the development and applications of next-generation low-cost skin electronics.