Nanostructured h-WO₃-Based Ionologic Gates with Enhanced Rectification and Transistor Functionality

Iontronic devices link ion-based transport with established electronic systems. Emerging capacitive devices, such as CAPode and G-Cap, feature diode-like rectification and transistor-like switching, respectively, through electrochemical capacitor functionality for enhanced energy storage and signal processing in next-generation low-power electronics. In this study, we present an asymmetric architecture based on nanostructured hexagonal tungsten oxide with significantly enhanced current rectification (with a rectification ratio of 58), providing a performant ionic transistor with 97.5% switching efficiency under only a 1 V bias. Key parameters, such as substrate materials, the mass ratio of the counter electrode to the working electrode, electrolyte composition, and concentration, are evaluated to reach the highest rectification ratios. The final device exhibited remarkable stability, maintaining performance for over 20,000 cycles without degradation. Additionally, integrating a third electrode into the optimized CAPode (termed G-Cap) allowed it to function as a transistor analogue, showing excellent switchability. The third gate electrode in the G-Cap plays a critical role in shifting the working electrode potential to reach the redox potential of tungsten oxide, enhancing the device functionality. As a proof of concept, the CAPodes were integrated into basic and complex logic gates under varying voltages and frequencies up to 1000 mHz, with output signals demonstrating robust performance. In addition, the logic operation metrics revealed a low threshold voltage of 0.4 V and a low power consumption of 2 μW. These results highlight the potential for expanded applications of this device structure.