Dielectric interface passivation of polyelectrolyte-gated organic field-effect transistors for ultrasensitive low-voltage pressure sensors in wearable applications

Polyelectrolyte-gated organic field-effect transistors (OFETs) are promising electronic devices for advanced sensing. However, real applications of polyelectrolyte-gated wearable OFET sensors are greatly limited by their severe hysteresis, poor stability, and low sensitivity. Here, a facile dielectric interface passivation strategy is developed for improving the performance of flexible OFETs with polyelectrolyte dielectrics towards ultrasensitive pressure sensors in wearable applications. Impressively, low-voltage polyelectrolyte-gated OFETs with negligible hysteresis and high mobility are achieved with beneficial effects of efficient leakage suppression, fine interfacial compatibility, and good resistance to moisture/ion migration induced by a nanoscale thin passivation layer of polystyrene at the polyelectrolyte/semiconductor interface. The OFETs with this novel composite dielectric of polystyrene/polyelectrolyte are further designed into flexible ultrasensitive pressure sensors with an exceptionally high sensitivity of 897.9 kPa⁻¹ at a low-operating voltage of -2 V. The flexible low-power OFET pressure sensors have good operational stability and can serve as wearable devices to monitor human arm movement. By integrating the OFET sensors as a wearable array, it can effectively detect pressure distribution and achieve high-resolution mapping and tactile imaging, demonstrating their good potentials for electronic skins, wearable technologies and multi-touch applications.