Graphical Abstract

A research team from China has developed a transparent smart radiation device (TSRD) to enhance thermal management for solar cells on spacecraft. These cells face extreme environmental challenges, particularly significant temperature variations, which can impact performance and light absorption. The TSRD, applied as a coating, uses a thermochromic material to adjust heat emission based on temperature changes.

The team utilized vanadium dioxide (VO2) as the thermochromic material, which shifts from an insulating to a metallic state at 68°C, altering its optical properties. A transparent substrate was incorporated to support this function. “Our research presents a multi-dimensional breakthrough, as we introduce a novel TSRD which resolves the long-standing challenge of balancing high visual transparency with effective thermal radiation control,” said Xiaohu Wu, the corresponding author.

Three substrates were tested via MATLAB simulation: single-layer indium tin oxide (ITO), single-layer silver (Ag), and a combined ITO/Ag/ITO structure. A protective barium fluoride (BaF?) layer was placed between the substrate and VO2. Optimized thicknesses included 0.015 μm for VO2, 1.5 μm for BaF?, 0.26 μm for single ITO, 0.003 μm for single Ag, and for the combined layer, 0.003 μm Ag with 0.01 μm ITO on each side.

The VO2/BaF2/ITO/Ag/ITO structure outperformed others, achieving visible spectrum transmission of 0.8 and 0.72 under high- and low-temperature conditions, respectively, with a solar absorption of 0.16 and infrared emission modulation of 0.51. The VO2/BaF2/ITO configuration recorded transmissions of 0.69 and 0.63, solar absorption of 0.28, and emission modulation of 0.44. The VO2/BaF2/Ag setup showed transmissions of 0.77 and 0.70, solar absorption of 0.15, and emission modulation of 0.52. “Moreover, the addition of a lossless dielectric layer as a protective coating not only preserves the excellent performance of the TSRD but also holds the potential to enhance its durability and lifespan,” Wu noted.

Looking ahead, the team plans to produce high-quality TSRD samples for testing in conditions mimicking space environments. “For experimental validation and engineering applications, we plan to prepare high-quality TSRD samples and conduct performance tests under extreme conditions simulating the space environment,” Wu stated. By comparing experimental results with theoretical models, the researchers aim to evaluate the TSRD’s stability, reliability, and long-term performance, laying the groundwork for its use in spacecraft thermal management systems.

This innovation was detailed in the study “Transparent smart radiation device for efficient thermal management of spacecraft solar cells,” published in Case Studies in Thermal Engineering. The research involved contributions from scientists at Northwestern Polytechnical University and the Shandong Institute of Advanced Technology in China.

by pv magazine