Low-voltage flexible organic transistors utilizing passivated polyelectrolyte dielectrics for tactile sensing and braille recognition

Abstract

Organic field-effect transistors (OFETs) utilizing polyelectrolyte dielectrics offer low-power operation and good signal amplification, making them well suited to pressure sensor applications. However, pristine polyelectrolyte dielectrics suffer from high leakage currents and instability under device operation. Here, we develop novel passivated polyelectrolyte dielectrics to enhance electrical performance of low-voltage flexible OFETs, achieving the reduced hysteresis and the significantly improved mobility from 0.04 to 1.17 cm² V⁻¹ s⁻¹. The optimized OFETs with passivated polyelectrolyte dielectrics are integrated as flexible pressure sensors, affording high sensitivity (297.2 kPa⁻¹) at −2 V, wide response range (0–70.1 kPa), and fast response in milliseconds. Inspired by human skin, the OFET pressure sensor successfully simulates biological synaptic behaviors, including excitatory postsynaptic currents, paired-pulse facilitation, and the transition from short-term memory to long-term memory, which are crucial for processing complex signals. Furthermore, intelligent touch recognition of braille characters with an accuracy of ∼98% is achieved by designing the low-voltage OFET pressure sensor array and combining it with algorithms. These results provide new insights into advanced dielectrics and low-power OFET sensors for potential applications in skin-like artificial synapses, and human–machine interaction systems.