Transparent and insulating silica aerogel composites doped with aluminum-doped zinc oxide for high-temperature solar thermal conversion

The development of high-performance transparent insulation is hindered by a fundamental conflict between solar transmittance and infrared thermal radiation suppression, particularly at high temperatures. This work presents a solution based on plasmonic engineering of silica aerogel composites. By incorporating aluminum-doped zinc oxide (AZO) nanoparticles, the Localized Surface Plasmon Resonance (LSPR) effect is leveraged to selectively block thermal radiation without significantly compromising solar transparency. The radiation properties of the AZO particles and aerogel composite are numerically investigated using the T-matrix and Monte Carlo methods. The greenhouse effect selection index (GESI) is introduced as a metric to evaluate the performance of such transparent insulation materials. The aerogel composite doped with 1500 nm particles of 0.5% volume fraction shows optimal performance below 650 K, reaching the highest GESI value. With a solar concentration ratio of 10, the maximum surface temperature of the collector can reach 1010 K. Furthermore, the experimental tests validate that at 400 °C, the thermal conductivity of the aerogel composite is reduced by 23.3% with 0.015% AZO doping. The results demonstrate that this plasmonic composite strategy offers an effective pathway for high-temperature solar thermal conversion.