pH-dependent doping level and optical performance of antimony-doped tin oxide nanocrystals as nanofillers of spectrally selective coating for energy-efficient windows

The optimal pH value of the titration endpoint remains uncertain for the synthesis of antimony-doped tin oxide by the co-precipitation method. In this study, the influence of the pH titration endpoint on doping level and optical performance was systematically studied. The phase composition, microstructure, the valence state of Sb ions and thermodynamic behaviors of antimony-doped tin oxide were comprehensively investigated. The UV–Vis–NIR transmittance spectra of ATO glass and SEM images of ATO coating were also studied. When the pH value of the titration endpoint was 6, the measured doping ratio of Sb was 10.81% which was close to the initial Sb doping level of 10%. In the meanwhile, the content of Sb⁵⁺ ions also reached the maximum value of 76.4%. Especially, the spectrally selective coating exhibited optimally spectral selectivity with the average visible light transmittance of 77.24% and the average near-infrared shielding ratio of 80.06% respectively. The results show that the doping level and optical properties of antimony-doped tin oxide certainly relied on the pH value of the titration endpoint. It is of great significance to scale up the production of antimony-doped tin oxide with superior near-infrared shielding performance and promote its practical application in the field of energy-efficient glazing.