Contact Modulated Ionic Transfer Doping in All-Solid-State Organic Electrochemical Transistor for Ultra-High Sensitive Tactile Perception at Low Operating Voltage

Ionic-electronic coupling across the entire volume of conjugated polymer films endows organic electrochemical transistors (OECTs) with high transconductance (g_m) and low operating voltage. However, OECTs utilize liquid electrolytes, which limit their long-term operation, reproducibility, and integration while solid electrolytes typically result in inefficient ion transport. Here, a solid polymer electrolyte is shown that can facilitate good electrochemical response in conjugated polymers and yield high OECT performance. This allows for the OECT-based pressure sensors, modulated through a pressure sensitive ionic doping process. The pressure sensor exhibits the highest sensitivity ever measured (≈10 000 kPa⁻¹) and excellent stability. Flexible sensor arrays achieve static capture of spatial pressure distribution and enable monitoring of dynamic pressure stimuli. The findings here demonstrate that all-solid-state OECTs are good candidates for providing rich tactile information, enabling applications for soft robotics, health monitoring, and human-machine interfaces.