Hydrogel ionic diode with ultra-high rectification ratio for ionic circuit

Abstract

Organisms transmit signals through complex ion systems, and signal transmission in artificial electronic circuits mainly depends on electrons. The development of rectifier ionic diode, grounded in ion transport principles, paves ways for artificial bionic circuit and seamless human–machine interaction. Among its pivotal performance indicators, the ion rectification ratio (IR) is of primal importance, facilitating enhanced ion selectivity, bolstered energy efficiency, and robust, high-performing operations. Here, hybrid hydrogel ionic diode based on chitosan (CS) doped with 5,10,15,20-tetrakis(4-aminophenyl)-21,23H-porphyrin (TAPP)/sodium polyacrylate (PAAs) doped with 5,10,15,20-tetrakis(4-sulfonatophenyl)-21,23H-porphyrin (TPPS) was constructed to achieve a high IR. This design achieved a remarkable feat by elevating the IR from 5.57 to an unprecedented 158.64, surpassing previous benchmarks set by hydrogel-based ionic diodes. Moreover, this study emphasizes the selectivity of polyelectrolytes to different porphyrin structures, as well as the charge properties of the groups carried by porphyrins. It delves into the fundamental mechanisms underpinning their interactions, providing a comprehensive understanding of their behavior. In order to demonstrate the excellent rectification characteristics and practical applicability of the CS-TAPP/PAAs-TPPS ionic diode, we successfully integrated it into the full-wave rectification and logic gate system. The full-wave rectifier can convert a 1.2 V sinusoidal voltage input to a 0.8 V full-wave voltage output. This shows the advantages of high IR ionic diodes. It offers insights for the development of high-performance hydrogel-based ionic diodes, and promotes the advancement of novel biomimetic devices and ionic circuits.