Bio-inspired microstructured janus films enabling continuous 24-hour thermoelectric energy harvesting
image: Biomimetic Janus moth-eye structures integrating a SiO2 radiative cooler and Si photothermal absorber enhance thermoelectric generator performance, delivering up to 108 mV and 41.5 μW/cm2. This study validates synergistic cooling-heating functions, clarifies key structural parameters, and advances rigid microstructured films for efficient, stable thermoelectric applications.
Credit: Nano Research, Tsinghua University Press
Global energy demand is surging alongside growing environmental pressures, making efficient, clean sustainable energy conversion technologies a top priority for researchers and industries worldwide. Thermoelectric generation (TEG) technology, which directly converts ubiquitous thermal energy into electricity, stands out as a promising green and low-carbon solution, with broad application potential in various scenarios.
Yet traditional TEG systems face significant bottlenecks: they rely heavily on single heat sources like industrial waste heat or body heat, or active cooling technologies, resulting in low energy density and high parasitic energy consumption. Additionally, the disconnect between hot-end design optimization and theory-experiment validation restricts their stable all-weather operation. The key challenge lies in constructing an efficient temperature gradient through the synergy of hot-end photothermal heating and cold-end radiative cooling to enable 24-hour continuous power generation.
To address this, Professor Yao Li's team from Harbin Institute of Technology, in collaboration with researchers from Liaoning Materials Laboratory, Far Eastern Federal University, and other institutions, has developed a bio-inspired Janus-structured metamaterial device. This innovative design synergistically integrates a microstructured SiO2 radiative cooling layer and a Si photothermal absorption layer, achieving a leapfrog improvement in thermoelectric performance.
Inspired by moth-eye microstructures, the device enhances absorption and emission properties through subwavelength engineering. The hot-end Si photothermal plate achieves a 95% absorption rate in the solar band, while the cold-end SiO2 cooling plate boasts an emissivity of 94.9% in the 8-13 μm atmospheric window, successfully establishing a steep temperature gradient.
"Our Janus device breaks through the limitations of traditional TEG systems by combining efficient photothermal conversion and radiative cooling," said Yao Li, corresponding author of the study. "This dual-mode design creates a stable temperature difference between the two ends of the TEG, enabling continuous power generation day and night."
Experimental verification confirms the device's exceptional performance: in summer, it achieves an average daytime output voltage of 70 mV and a peak voltage exceeding 108 mV. Under open-system conditions, the power density reaches 41.5 μW/cm² with a maximum temperature difference of 8.9 °C, outperforming existing similar technologies. Notably, the device maintains stable voltage output at night through radiative cooling, demonstrating excellent adaptability across different seasons.
The device's core structure centers on a commercial TEG module, with a microstructured Si photothermal plate (hot end) and a microstructured SiO2 radiative cooling plate (cold end) integrated on both sides. Silver mirror reflection and thermal insulation foam encapsulation optimize energy utilization. The Si photothermal plate features a tapered array (28° cone angle, 1 μm height), while the SiO2 cooling plate has a truncated microcone array (0.6 μm top diameter, 1.2 μm bottom diameter), both optimized via FDTD simulations for optimal optical performance.
Indoor xenon lamp simulations show the Si photothermal plate reaches 51 °C within 150 seconds, forming a 21.7 °C temperature difference with the SiO2 cooling plate. Outdoor tests reveal the Si photothermal plate can reach 58 °C (25.2 °C above ambient), while the SiO2 cooling plate can be 9 °C below ambient, achieving a maximum temperature difference of 34.3 °C.
A 24-hour continuous test confirms the device's all-weather operation capability, with uninterrupted voltage output and a peak exceeding 55 mV. In open-system outdoor tests, it maintains a maximum temperature difference of 8.6 °C despite natural convection, with the TEG1-127 model delivering an average voltage of 30.6 mV-far superior to the 11.6 mV of TEG1-199.
"This study provides a new approach to hot-end design and system validation for TEG technologies," added Hongbo Xu, another corresponding author. "Our findings lay a solid technical foundation for the commercialization and widespread application of TEG systems in building energy conservation, automotive glazing, and adaptive thermal control devices."
Other contributors include Honglin Li, Zhenmin Ding, Xin Li, Jiupeng Zhao, Yan Liu, Ana Sofia Oliveira Henriques Moita, and Aleksandr Kuchmizhak from institutions including Harbin Institute of Technology, Liaoning Academy of Materials, Northeast Forestry University, Universidade de Lisboa, and Far Eastern Branch of Russian Academy of Sciences
This work was supported by the National Key R&D Program of China (2022YFB3902704), the National Natural Science Foundation of China (5247020620), International Research Programs and Strategic Innovative Programs of National Key R&D Program of China (2024YFE0105500), the Natural Science Foundation of Heilongjiang Province (LH2023E034).
DOI Link:
https://doi.org/10.26599/NR.2026.94908403
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