Robust High Thermoelectric Harvesting Under a Self‐Humidifying Bilayer of Metal Organic Framework and Hydrogel Layer

Robust thermoelectric harvesting is explored from a proton‐doped mixed ionic conductive (PMIC) film under water‐harvesting metal organic framework (MOF) film coupled with hydrogel layer (MOF/HG). As a PMIC, highly doped poly(3,4‐ethylenedioxythiophene)s with poly(styrene sulfonate) (PEDOT:PSS) is prepared by precisely controlling the proton doping to afford a stable and high thermoelectric PMIC. Among the PMICs, the PEDOT:PSS film doped with 30 wt% of poly(styrene sulfonic acid) (PSSH) recorded a Seebeck coefficient of over 16.2 mV K −1 and a thermal voltage of 81 mV for a temperature gradient (Δ T ) of 5 K. The thermal charging on PMICs afforded high thermal voltage and current output, reproducibly, to show cumulative thermoelectric nature. Environmentally sustainable thermoelectric harvesting is achieved from a PMIC under a MOF/HG, prepared by water‐harvesting MOF‐801 coupled with a HG layer, to provide constant relative humidity of 90% and V oc over 72 h at ambient condition.