Full solar-spectral reflectance of ZnO QDs/SiO2 composite pigment for thermal control coating

Abstract Thermal control coatings play an important role in the long-term operation of spacecrafts. The next generation of outer space technology demands thermal control coatings for high reflectivity not only in the visible and infrared but also in the ultraviolet spectral range. In this paper, ZnO quantum dots (QDs) and SiO2 composite pigments were prepared by the rapid injection sol-gel method and subsequent sintering. A high reflectance above 60% in the full solar-spectral range of 200–2600 nm was reached with the composite pigments at an optimized sintering temperature. The structural and optical properties of the ZnO QDs/SiO2 composite pigments with respect to the sintering temperature are studied using X-ray powder diffraction, Scanning and Transmission electron microscopy, Raman scattering, Photoluminescence, Fourier-transform infrared spectroscopy. The mechanism enabling the full solar spectral reflectance is discussed in terms of the quantum confinement effect and the Kubelka–Munk theorem.