Near-Infrared Responsive Ionoelastomer Junction Enabling Switchable Ionic Logic Gate

Despite the significant progress in the development of ionic junctions of two types of ionic conductors for ionic current rectification, reminiscent to electronic p- and n-type junctions, stimuli-responsive ionic junctions wherein stimuli reversibly control current rectification are seldom demonstrated. Here, we present a near-infrared (NIR)-responsive ionic junction and its application as a switchable logic gate. The NIR- responsive ionic junction is developed with a bilayer of ionoelastomers: liquid-free ionic conductors with mobile cations (p-type) and anion counterions (n-type) mixed with NIR-responsive 2D MXene (Ti₃C₂T_<i>x</i>) nanosheets sandwiched between two liquid metal electrodes. The study revealed that two types of MXene with positive and negative surface potentials incorporated into p- and n-type ionoelastomers, respectively, facilitated the diffusion of mobile ions. This resulted in an enhanced current rectification of an ionic diode. The rectification of an ionic junction is further increased upon NIR exposure to the device due to the photothermal energy conversion of MXene. A facile control of the rectification ratio with both exposure time and power of NIR enabled the development of a switchable ionic logic gate. Herein, the AND-to-OR gate transition was reversibly manipulated by NIR exposure and device cooling programmed to the two ionic junctions in series.