A Mixed Ion‐Electron Thermoelectric Generator With Organic Semiconductor Ionogels for Continuous Heat Harvesting

Abstract

Ionic thermoelectric (TE) materials can exhibit a thermopower higher than that of electronic TE materials by 2–3 orders in magnitude, but their practical application is limited by the inability to sustain electrical output under steady temperature gradient due to blocked ionic transport at the interfaces between electrodes and ionic TE materials. Here, we demonstrate continuous TE conversion enabled by coupled ionic–electronic transport in an organic semiconductor ionogel. By incorporating a conjugated molecule, Rhodamine 101, into an ionogel composed of 1‐ethyl‐3‐methylimidazolium dicyanamide (EMIM:DCA) and gelatin, electronic pathways can be established to enable sustained electricity generation. The R101 ionogels can exhibits a thermopower of 17.55 mV/K and an ionic conductivity of 1.45 S/m, and it can supply steady output voltage even under steady temperature gradient. Unlike previous approaches based on conductive fillers, this strategy can improve the ionic conductivity without lowering the thermopower. This work establishes a new approach for integrating ionic and electronic conductions to overcome a fundamental limitation of ionic thermoelectrics and thus opens new opportunities for continuous waste heat harvesting.