Large-Scale Nanofiber Manufacturing| Large-area radiation-modulated thermoelectric fabricsfor high-performance thermal management and electricity generation

Soochow University《Science Advances》: Large-Area Radiation-Modulated Thermoelectric Fabrics for High-Performance Thermal Management and Electricity Generation

Energy harvesting from environments or human bodies for self-powered sensors, energy storage, and wearable electronics has attracted significant attention. Thermoelectric generator (TEG) fibers offer advantages like simple structure, good mechanical flexibility, and direct thermoelectric conversion, but face challenges in maintaining stable temperature gradients and scalable manufacturing. Radiation modulation technology can enhance the temperature difference (ΔT) of thermoelectric fabrics for thermal comfort and high electrical output, yet challenges remain in maintaining stable temperature gradients and achieving commercial-scale production.

Recently, Prof. Zhang Keqin, Prof. Liao Liangsheng, and Dr. Zhuo Mingpeng from Soochow University reported the fabrication and performance of large-area radiation-modulated thermoelectric fabrics for high-performance thermal management and electricity generation. They prepared PVDF-HFP radiative cooling fiber membranes via electrospinning and carbon nanotube (CNT)-based photothermal/thermoelectric arrays via screen printing, combining them into fabrics capable of thermal management and thermoelectric conversion, providing a new approach for powering wearable electronics.The resulting thermoelectric fabric (0.2 m²) achieved a ΔT of 37 K under ~800 W/m² solar intensity with a peak power density of 0.20 mW/m², leveraging CNTs' excellent photothermal properties. This study offers a practical solution for simultaneously addressing thermal management and power generation in self-powered wearable applications through efficient solar energy harvesting. The research was published in Science Advances as "Large-area radiation-modulated thermoelectric fabrics for high-performance thermal management and electricity generation."

Figure 1. Design and fabrication of radiation-modulated thermoelectric fabrics.

Design and Fabrication of Radiation-Modulated Thermoelectric Fabrics:

PVDF-HFP Nanofiber Membrane Preparation: Using DMF and acetone as solvents, electrospinning produced PVDF-HFP nanofiber membranes with smooth surfaces, diameters of 0.3–1.6 μm (average ~0.8 μm). The membrane showed >96.9% solar reflectance (0.3–2.5 μm) and 96.8% mid-infrared emissivity, achieving a 9.6°C lower equilibrium temperature than white fabric under 1-sun AM 1.5 irradiation after 1500 s.

Screen-Printed Photothermal/Thermoelectric Arrays: CNT-based ink was used for its high viscosity, low toxicity, chemical stability, conductivity, and Seebeck coefficient. A 560-pair CNT/Ag array was printed on 1 m × 0.2 m fabric, demonstrating high pattern flexibility (e.g., "Soochow University" logo). Infrared imaging confirmed the CNT pattern's photothermal stability over 10 cycles, with temperature increase proportional to solar intensity.

Figure 2. Photothermal performance of screen-printed photothermal/thermoelectric arrays.

Thermoelectric Array Performance: A 28-pair array on 10 cm × 10 cm white fabric showed voltage increasing from 0.58 mV to 4.63 mV as ΔT rose from 1 K to 8 K (total Seebeck coefficient: 1.16 mV/K). The power density reached 1.04 W/m² at ΔT = 9 K (short-circuit current: ~0.8 A). Performance remained stable after washing, long-term storage, and bending cycles.

Output Performance: Combining PVDF-HFP membranes with CNT arrays created fabrics with tunable ΔT via coverage ratio (x:y) and pattern size (a:b). At 50% coverage and 0.42 pattern ratio, the fabric achieved ΔT = 37.1°C, 47.9 mV output, and 0.32 mW/m² power density under 1-sun irradiation. Outdoor tests showed output voltage tracking solar irradiance (peak: 42.7 mV at noon) and 0.5 mV nighttime output via radiative cooling. The breathable fabric also enabled motion sensing and powered small wearable devices (e.g., LEDs, timers).

Figure 3. Thermoelectric performance of the thermoelectric arrays

Figure 4. Output performance of radiation-modulated thermoelectric fabrics.

Figure 5. Applications of the radiation-modulated thermoelectric fabrics.

This work demonstrates scalable, flexible thermoelectric fabrics integrating electrospun radiative cooling membranes and CNT arrays for precise ΔT control and enhanced energy conversion. With 6.67 V/m² output at 800 W/m² solar flux, the fabric shows promise for wearable solar harvesting, sensing, and electronics, offering a novel approach to utilizing low-grade environmental heat.