Bio-inspired microstructured Janus films enabling continuous 24 h thermoelectric energy harvesting

Radiative cooling technology shows promise for improving thermoelectric generator (TEG) efficiency, but challenges in hot-end design and model validation remain. To address this, a Janus moth-eye-inspired device was developed, leveraging microstructure-enhanced absorption/emission. This device combines a SiO2 radiative cooler with a radiative Si photothermal absorber in a synergistic configuration. When integrated into a commercial TEG for gradient-based power generation, the Janus composite demonstrated exceptional performance: a peak output voltage of 108 mV, an average daytime voltage of 70 mV under summer daylight conditions, and an output power density reaching 41.5 μW/cm2. This study systematically investigates the key parameters of the Janus structure and their impact on the voltage output. Furthermore, it experimentally validates the efficacy of both the SiO2 radiative cooler and Si photothermal absorber in boosting TEG performance. These findings establish a foundation for future research on stable, rigid biomimetic microstructured thin films for advanced thermoelectric applications.