Integrated Thermoelectric Generation System for Sustainable All-Day Power Supply Based on Solar Energy and Radiative Cooling

Thermoelectric generators have a promising application in the field of sustainable energy due to their ability to utilize low-grade waste heat and their high reliability. The sun radiates a large amount of energy to the earth, yet most of which is wasted. Efficient utilization of solar energy can be achieved by integrating a solar absorber, phase change material, and Fresnel lens with thermoelectric generators. In this work, multiwalled carbon nanotubes are mixed with polydimethylsiloxane as a solar absorber and achieve up to 99% absorption of sunlight. Meanwhile, the solar absorber as a radiative cooler also exhibits high emissivity in the atmospheric window, and a cooling effect of 7.3 K from the ambient temperature can be realized at night. Paraffin wax as a phase change material realizes heat storage during the day and release at night. The Fresnel lens realizes a high degree of convergence of sunlight over a large area, obtaining a higher output performance at a lower cost. The multienergy integrated and synergistic thermoelectric generation system achieves an output power density of 4.1 mW/cm² during the day and a peak power density of 0.2 mW/cm² during the night, which can meet the demand for ab uninterrupted power supply to electronic devices. This work realizes the efficient utilization of solar energy and provides an option for thermoelectric application.