Thermally Programmable Liquid-Crystalline Thermoelectric Ionogels

Ionic thermoelectric effect has emerged as a new realm for ionic thermoelectric supercapacitors, energy harvesters, fluorescence ion sensing, and self-healable materials. However, despite significant improvement of ionic thermoelectric performance and several attempts to extend to include other mechanical properties, a temperature-programmable function has not been integrated with ionic thermoelectric materials. Herein, we synthesized thermally programmable ionogels <i>via</i> photopolymerization of ionic monomers and hydrophobic nematic monomers in the presence of an ionic liquid. A liquid-crystalline ionogel film showed reversible temperature programmability at designed temperature, at which temperature the nematic-isotropic phase transition occurs by monitoring with polarized optical microscope. The liquid-crystalline ionogel film showed a phase-controlled ionic Seebeck coefficient. To enhance the carrier transport for thermoelectric performance, doped carbon nanotubes were introduced for thermoelectric ionogel device. Taking advantage of high thermoresponsive thermoelectric output, the liquid-crystalline ionogel film was used to demonstrate a self-detectable and wireless fire alarm, which enables detection of elevated temperatures with the naked eye by integrated as a thermal switch for an electrochromic window, a liquid crystal display, or a light-emitting diode. The ionogels could benefit in exploiting autonomous thermoresponsive electronics that can be used to detect and view temperature changes in the environment.