Integrated Hydrogel-Based Photothermoelectric Device for Energy Harvesting

Currently, thermoelectric generators are centered around harnessing the temperature difference between body heat and the environment for electricity generation. Nevertheless, in certain regions with year-round warm climates, the effective temperature difference (Δ<i>T</i>) is frequently markedly inadequate. Therefore, it is necessary to explore novel thermoelectric devices that are not driven by body heat. In this study, an integrated photothermoelectric (PTE) device was fabricated. This device consists of a cotton/PPy photothermal layer and a thermoelectric hydrogel, with [Fe(CN)₆]^3-/4- serving as a redox couple. The PTE device demonstrated remarkable stability, sustaining a consistent voltage output of 31.42 mV under the solar intensity of 150 mW cm^-2. When four PTE devices were connected in series and integrated with a voltage amplifier, they exhibited the capacity to power small electronic devices under illumination. Intriguingly, the PTE devices also functioned as thermogalvanic units intrinsically. In the absence of light, they retained their electricity-generation ability by harnessing body heat. This research significantly broadens the application scope of gel-based thermoelectric materials and offers novel insights for the design of integrated PTE devices.